Sub Pirates World Submarines

The concept of an underwater boat has roots deep in antiquity. Although there are images of men using hollow sticks to breathe underwater for hunting at the temples at Thebes, the first known military use is of divers being used to clear obstructions during the siege of Syracuse (about 413 BC), according to the History of the Peloponnesian War. At the siege of Tyre in 332 BC divers were again used by Alexander the Great, according to Aristotle. Later legends from Alexandria, Egypt, in the 12th century AD suggested that he had used a primitive submersible for reconnaissance missions. This seems to have been a form of diving bell, and was depicted in a 16th-century Islamic painting. Abraham ibn Ezra (about 1150) interprets Noah's Ark as being a vessel that floated for 40 days on water, after which it floated to the surface.

After various plans for submersibles or submarines during the Middle-Ages, the Englishman William Bourne designed a prototype submarine in 1578, although these ideas never got beyond the planning stage. However, the first submersible proper to be actually built in modern times was constructed in 1605 by Magnus Pegelius but this became buried in mud.

The first successful submarine was built in 1620 by Cornelius Jacobszoon Drebbel, a Dutchman in the service of James I; it may have been based on Bourne's design. It was propelled by oars. The precise nature of the submarine type is a matter of some controversy; some claim that it was merely a bell towed by a boat. Two improved types were tested in the Thames between 1620 and 1624.

Though the first submersible vehicles were tools for exploring under water, it did not take long for inventors to recognize their military potential. The strategic advantages of submarines were set out by Bishop John Wilkins of Chester in Mathematicall Magick in 1648:

1.	Tis private: a man may thus go to any coast in the world invisibly, without discovery or prevented in his journey.
2.	Tis safe, from the uncertainty of Tides, and the violence of Tempests, which do never move the sea above five or six paces deep. From Pirates and Robbers which do so infest other voyages; from ice and great frost, which do so much endanger the passages towards the Poles.
3.	It may be of great advantages against a Navy of enemies, who by this may be undermined in the water and blown up.
4.	It may be of special use for the relief of any place besieged by water, to convey unto them invisible supplies; and so likewise for the surprisal of any place that is accessible by water.
5.	It may be of unspeakable benefit for submarine experiments.

Between 1690 and 1692, the French physicist Denis Papin, designed and built two submarines. A detailed description of his work is given in the book named "recueil de diverses pièces" (1695). The first design (1690) was a strong and heavy metallic square box, equipped with an efficient pump. Once the hull is in the water, and weights loaded on board, the "man hole" is bolted, and it is time to pump air to raise the inner pressure. When the barometer shows that air pressure inside is high enough, holes F on the floor can be opened, to let the operator intake the necessary amount of water. This first machine was destroyed by accident, before it was tested in water.
Denis Papin's submarine, second design, 1690.

The second design was built in 1692 : the hull has now an oval shape, naturally resistant to the outside pressure : outside air goes in and out freely in the hull, thanks to a centrifugal air pump. After having loaded the hull with enough solid weight, the top of the hull nearly match the water surface, and the "man hole" has to be bolted. A water pump allows then to take in or out a volume of water, to control buoyancy. According to some sources, a spy of Leibniz, called Haes related that Papin and another man, met success in experimenting this second design, on the river Lahn.

By the 17th century the Ukrainian Cossacks were using a riverboat called the chaika (gull) that was used underwater for reconnaissance and infiltration missions. This seems to have been closer to (and may have been developed from) Aristotle's description of the submersible used by Alexander the Great. The Chaika could be easily capsized and submerged so that the crew was able to breathe underneath (like in a modern diving bell) and propel the vessel by walking on the bottom of river. Special plummets (for submerging) and pipes for additional breathing were used.

By 1727, 14 types of submarine had been patented in England. In 1749 the Gentlemen's Magazine described a proposal made by Giovanni Borelli in 1680 for a boat with goatskins in the hull, each being connected to an opening. The boat would have been submerged by letting water into the goatskins and surfaced by forcing water out by a twisting rod. This seems to be the first approach to the modern ballast tank.

The first military submarine was Turtle in 1776, a hand-powered egg-shaped device designed by the American David Bushnell, to accommodate a single man. It was the first verified submarine capable of independent underwater operation and movement, and the first to use screws for propulsion. During the American Revolutionary War, Turtle (operated by Sgt. Ezra Lee, Continental Army) tried and failed to sink a British warship, HMS Eagle (flagship of the blockaders) in New York harbor on September 7, 1776. There is no record of any attack in the ships' logs.

In 1800, France built a human-powered submarine designed by Robert Fulton, the Nautilus. It also had a sail for use on the surface and so was the first known use of dual propulsion on a submarine. It proved capable of using mines to destroy two warships during demonstrations. The French eventually gave up with the experiment in 1804, as did the British when they later tried the submarine.

During the War of 1812, in 1814 Silas Halsey lost his life while using a submarine in an unsuccessful attack on a British warship stationed in New London harbor.

In 1834 a Russian naval designer Karl Shilder built and tested an all-metal submarine in Saint Petersburg. His submarine was equipped by 6 Congreve rockets.

In 1851, a Bavarian artillery corporal, Wilhelm Bauer, took a submarine designed by him called the Brandtaucher (fire-diver) to sea in Kiel Harbour. This submarine was built by August Howaldt and powered by a treadwheel. It sank but the crew of 3 managed to escape. The submarine was raised in 1887 and is on display in a museum in Dresden.

During the American Civil War, the Union was the first to field a submarine. The French-designed Alligator was the first U.S. Navy sub and the first to feature compressed air (for air supply) and an air filtration system. It was the first submarine to carry a diver lock, which allowed a diver to plant electrically detonated mines on enemy ships. Initially hand-powered by oars, it was converted after 6 months to a screw propeller powered by a hand crank. With a crew of 20, it was larger than Confederate submarines. Alligator was 47 feet (14.3 m) long and about 4 feet (1.2 m) in diameter. It was lost in a storm off Cape Hatteras on April 1, 1863 while uncrewed and under tow to its first combat deployment at Charleston.

The Intelligent Whale was built by Oliver Halstead and tested by the U.S. Navy after the American Civil War and caused the deaths of 39 men during trials.

The Confederate States of America fielded several human-powered submarines, including CSS H. L. Hunley (named for its designer and chief financier, Horace Lawson Hunley). The first Confederate submarine was the 30-foot-long (9.1 m) Pioneer, which sank a target schooner using a towed mine during tests on Lake Pontchartrain but it was not used in combat. It was scuttled after New Orleans was captured and in 1868 was sold for scrap; the similar Bayou St. John Confederate Submarine is preserved in the Louisiana State Museum. CSS Hunley was intended for attacking Union ships that were blockading Confederate seaports. The submarine had a long pole with an explosive charge in the bow, called a spar torpedo. The sub had to approach an enemy vessel, attach the explosive, move away, and then detonate it. It was extremely hazardous to operate, and had no air supply other than what was contained inside the main compartment. On two occasions, the sub sank; on the first occasion half the crew died, and on the second, the entire eight-man crew (including Hunley himself) drowned. On February 17, 1864, Hunley sank USS Housatonic off the Charleston Harbor, the first time a submarine successfully sank another ship, though it sank in the same engagement shortly after signaling its success. Submarines did not have a major impact on the outcome of the war, but did portend their coming importance to naval warfare and increased interest in their use in naval warfare.

The Submarino Hipopótamo was the first submarine in South America built and tested in Ecuador on September 18, 1837. It was designed by Jose Rodriguez Lavandera, who successfully crossed the Guayas River in Guayaquil accompanied by Jose Quevedo. Rodriguez Lavandera had enrolled in the Ecuadorian Navy in 1823, becoming a Lieutenant by 1830. The Hipopotamo crossed the Guayas on two more occasions, but it was then abandoned because of lack of funding and interest from the government. Today, few engravings and a scale model of the original design is preserved by the Maritime Museum of the Ecuadorian Navy.

The "Flach", was commissioned in 1865 by the Chilean government during the war between Chile and Peru against Spain (1864 -1866). It was built by the German engineer Karl Flach. The submarine sank during tests in Valparaiso bay on May 3, 1866, with the entire eleven-man crew.

In 1879, the Peruvian government, during the War of the Pacific commissioned and built a submarine. That was the fully operational Toro Submarino, which nevertheless never saw military action before being scuttled after the defeat of that country in the war to prevent its capture by the enemy.

The first submarine that did not rely on human power for propulsion was the French Navy submarine Plongeur, launched in 1863, and equipped with a reciprocating engine using compressed air from 23 tanks at 180 psi.

The Ictineo II, designed by Narcís Monturiol, was the first combustion driven submarine and the first fully functional submarine.

Originally launched in 1864 as a human-powered vessel, propelled by 16 men, it was converted to peroxide propulsion and steam in 1867. The 14 meter (46 ft) craft was designed for a crew of two, could dive to 30 metres (96 ft), and demonstrated dives of two hours. On the surface it ran on a steam engine, but underwater such an engine would quickly consume the submarine's oxygen; so Monturiol invented an air-independent propulsion system. As the air-independent power system drove the screw, the chemical process driving it also released oxygen into the hull for the crew and an auxiliary steam engine. Apart from being mechanically powered, Monturiol's pioneering double hulled vessels also solved pressure, buoyancy, stability, diving and ascending problems that had bedeviled earlier designs.

In 1870, French writer Jules Verne published the science fiction classic Twenty Thousand Leagues Under the Sea, which concerns the adventures of a maverick inventor in Nautilus, a submarine more advanced than any that existed at that time. The story inspired inventors to build more advanced submarines.

In 1878 a Manchester curate, the Reverend George Garrett obtained a patent for "Improvements in and appertaining to Submarine or Subaqueous Boats" and set up a company to build them. His first prototype Resurgam was hand powered and next year the company built the steam-powered Resurgam II at Birkenhead. Garrett intended to demonstrate the 12 m long vehicle to the Royal Navy at Portsmouth, but had mechanical problems, and while under tow the submarine was swamped and sank off North Wales.

The first submarine built in series, however, was human-powered. It was the submarine of the Polish inventor Stefan Drzewiecki - 50 units were built in 1881 for the Russian government. In 1884 the same inventor built an electric-powered submarine.

Discussions between George Garrett and Swede Thorsten Nordenfelt led to a series of steam powered submarines. The first was the Nordenfelt I, a 62 ton, 64 foot long spindle shaped vessel similar to the Resurgam II, with a range of 150 miles and armed with a single external torpedo, completed in 1885. Greece, fearful of the return of the Ottomans, purchased it (the submarine was shipped in parts and assembled by the Ifaistos machine works in Piraeus). Due to problems during testing, it was never operationally utilized. Nordenfelt then built at Chertsey the Nordenfelt II (Abdülhamid) in 1886 and Nordenfelt III (Abdülmecid) in 1887, a pair of 98 foot long submarines with twin torpedo tubes, for the Ottoman navy. The Abdülhamid achieved fame as the world's first submarine to fire a torpedo underwater. Nordenfelt's efforts culminated in 1887 with the Nordenfelt IV, with twin motors and twin torpedoes, built at Barrow-in-Furness. It was sold to the Russians, but proved unstable, ran aground and was scrapped.

The first fully capable military submarine was the electrically powered vessel built by the Spanish engineer and sailor, Isaac Peral, for the Spanish Navy. It was launched on September 8, 1888. It had two torpedoes, new air systems, hull shape and propeller and cruciform external controls anticipating later designs. Its underwater speed was ten knots. When fully charged it was the fastest submarine yet built, with performance levels (except for range) that matched or exceeded those of First World War U-boats. In June 1890 Peral's submarine launched a torpedo under the sea. It was also the first submarine to incorporate a fully reliable underwater navigation system. However, conservatives in the naval hierarchy terminated the project despite two years of successful tests.

Also marking an important milestone in the development of military submarines was the French navy's Gymnote, launched on September 24, 1888. The electrically powered Gymnote was another fully functional military submarine. It completed 2,000 dives successfully. However, like the Peral, its range was also limited by its reliance on batteries.

Many more submarines were built at this time by various inventors, such as Simon Lake and Oliver Halstead, but they were not to become effective weapons until the 20th century.

The turn of century era marked a pivotal time in the development of submarines, with a number of important technologies making their debut, as well as the widespread adoption and fielding of submarines by a number of nations. Diesel Electric propulsion would become the dominant power system and instruments such as the periscope would become standardized. Large numbers of experiments were done by countries on effective tactics and weapons for submarines, all of which would culminate in them making a large impact on 20th century warfare.

The Irish inventor John Philip Holland built a model submarine in 1876 and a full scale one in 1878, followed by a number of unsuccessful ones. In 1896 he designed his Holland Type VI submarine, that, for the first time, made use of internal combustion engine power on the surface and electric battery power for submerged operations. Launched on 17 May 1897 at Navy Lt. Lewis Nixon's Crescent Shipyard in Elizabeth, New Jersey, the Holland VI was (eventually) purchased by the United States Navy on 11 April 1900, becoming the United States Navy's first commissioned submarine and renamed USS Holland. A prototype version of the A-class submarine (Fulton) was developed (soon after) at Crescent under the supervision of naval architect Arthur Leopold Busch for the newly reorganized Electric Boat Company in 1900. The Fulton was never commissioned by the United States Navy and was sold to the Imperial Russian Navy in 1905. Many countries became interested in Holland's (weapons) product and purchased "the rights" to build them during this time period. The Holland Torpedo Boat Company/Electric Boat Company became General Dynamics "Cold War" progeny and is arguably the builder of the world's most technologically advanced submarines to this day.

The construction of the A-class boats soon followed the prototype (Fulton). The submarines were built at two different shipyards on both coasts of the United States. See: Union Iron Works/Mare Island Naval Shipyard and Crescent Shipyard. In 1902, Holland received U.S. Patent 708,553 for his relentless pursuit to perfect the modern submarine craft. Some of his vessels were purchased by the United States and other "technologically advanced" nations such as the United Kingdom, the Imperial Russian Navy, the Royal Netherlands Navy and the Imperial Japanese Navy. Mr. Holland was no longer in control of his company at this point—as others were formally engaged in transactions with many other foreign nations around the world at this time. The Type VII design was also adopted by the Royal Navy as well (with Holland's input, as the Holland class submarine, including Britain's Holland #1).

On 14 June 1904 the Imperial Japanese Navy (IJN) placed an order for five Holland Type VII submersibles, which were built in Quincy, Massachusetts at the Fore River Yard, and shipped to Yokohama, Japan in sections; all five machines arrived on 12 December 1904. Under the supervision of naval architect Arthur L. Busch, the imported Hollands were re-assembled, and the first submersibles were ready for combat operations by August 1905, however hostilities were nearing the end by that date, and no submarines saw action during the war.

In 1904 Kawasaki purchased rights from Holland to manufacture two modified submersibles at Kobe, Japan. The two Kaigun Hollands were numbered 6 & 7, and were both launched on 28 September, but a year apart, in 1905 and 1906 respectively. The #6 & #7 "Kawasaki" Hollands displaced 63/95 submerged tons, and measured 73'/84' in over all length, respectively; each vessel measured approximately 7' in width (beam). The two submarines had attained nearly a 50% increase in horsepower and a 25% decrease in fuel consumption over the five imported Hollands, which displaced over a 100 submerged tons each, and measured 67' in over all length, and were 11' wide (beam). However, the two Kawasaki machines could only launch one 18" torpedo and required 14 crewmen to operate, whilst the imported Hollands could fire two 18" torpedoes and only needed 13 men to operate. Kaigun Holland #6, the first submarine built in Japan, was removed from the naval list in 1920 and preserved as a memorial in Kure, Japan.

The Imperial Russian Navy (IRN) preferred the German constructed submersibles built by the Germaniawerft shipyards out of Kiel. In 1903 Germany successfully completed its first fully functional engine-powered submarine, Forelle (Trout). This vessel was sold to Russia in 1904 and shipped via the Trans-Siberian Railway to the combat zone during the Russo-Japanese War.

Due to the naval blockade of Port Arthur, Russia sent their remaining submarines to Vladivostok, and by the end of 1904 seven subs were based there. On 1 January 1905, the IRN created the world's first operational submarine fleet around these seven submarines. The first combat patrol sent out by the newly created IRN submarine fleet occurred on 14 February 1905 and was carried out by Delfin and Som, with each patrol normally lasting about 24 hours. Som had her first enemy contact on 29 April, when she was fired upon by IJN torpedo boats, which withdrew shortly after opening fire; resulting in no casualties or damage to either combatant. A second contact occurred on 1 July 1905 in the Tartar Strait when the IRN sub Keta was spotted by two IJN torpedo boats. Unable to submerge quick enough, she was unable to obtain a proper firing position, and both combatants broke contact.

In 1904, the IRN ordered several more submersibles from the Keil shipyard, the Karp class. One example was modified and improved, then commissioned into the Imperial German Navy in 1906 as its first U-boat, U-1. In 1919, U-1 was retired and is currently preserved and on display in the Deutsches Museum in Munich.

The first time military submarines had significant impact on a war was in World War I. Forces such as the U-boats of Germany saw action in the war on Allied commerce (Handelskrieg). The submarine's ability to function as a practical war machine relied on new tactics, their numbers, and submarine technologies such as combination diesel/electric power system that had been developed in the preceding years. More like submersible ships than the submarines of today, Submarines operated primarily on the surface using standard engines, submerging occasionally to attack under battery power. They were roughly triangular in cross-section, with a distinct keel, to control rolling while surfaced, and a distinct bow.

At the start of the war Germany had 48 submarines in service or under construction, of which 29 were operational. Initially Germany followed the international "Prize Rules", which required a ship's crew to be allowed to leave before sinking their ship. After the British ordered transport ships to act as auxiliary cruisers, the German navy adopted unrestricted submarine warfare;[citation needed] generally no warning was given before an attack was made. During the war 360 submarines were built but 178 were lost, and all the rest were surrendered at the end.

There were 77 operational submarines at the beginning of the war, with 15 under construction. The main type was the "E class", but several experimental designs were built, including the "K class", which had a reputation for bad luck, and the "M class", which had a large deck-mounted gun. The "R class" was the first boat designed to attack other submarines. British submarines operated in the Baltic, North Sea and Atlantic, as well as in the Mediterranean and Black Sea. Over 50 were lost from various causes during the war.

France had 62 submarines at the beginning of the war, in 14 different classes. They operated mainly in the Mediterranean, and in the course of the war, 12 were lost.
Russia

The Russians started the war with 58 submarines in service or under construction. The main class was the "Bars" with 24 boats. Twenty-four submarines were lost during the war.

Various new submarine designs were developed during the interwar years. Among the most notorious ones were submarine aircraft carriers, equipped with waterproof hangar and steam catapult and which could launch and recover one or more small seaplanes. The submarine and her plane could then act as a reconnaissance unit ahead of the fleet, an essential role at a time when radar still did not exist. The first example was the British HMS M2, followed by the French Surcouf, and numerous aircraft-carrying submarines in the Imperial Japanese Navy. The 1929 Surcouf was also designed as an "underwater cruiser," intended to seek and engage in surface combat.

Although Germany had been banned from having submarines, construction started in secret during the 1930s. When this became known the Anglo-German Treaty of 1936 allowed Germany to achieve parity in submarines with Britain.
Submarines during World War II

Germany started the war with only 65 submarines, with 21 at sea when war broke out. However Germany soon built up the largest submarine fleet during World War II. Due to the Treaty of Versailles limiting the surface navy, the rebuilding of the German surface forces had only begun in earnest a year before the outbreak of World War II. Having no hope of defeating the vastly superior Royal Navy decisively in a surface battle, the German High Command planned on fighting a campaign of "Guerre de course" (Merchant warfare), and immediately stopped all construction on capital surface ships, save the nearly completed Bismarck-class battleships and two cruisers, and switched the resources to submarines, which could be built more quickly. Though it took most of 1940 to expand the production facilities and get the mass production started, more than a thousand submarines were built by the end of the war.

Germany put submarines to devastating effect in World War II during the Battle of the Atlantic, attempting but ultimately failing to cut off Britain's supply routes by sinking more ships than Britain could replace. The supply lines were vital to Britain for food and industry, as well as armaments from the United States. Although the U-boats had been updated in the intervening years, the major innovation was improved communications, encrypted using the famous Enigma cipher machine. This allowed for mass-attack tactics or "wolfpacks" (Rudel), but was also ultimately the U-boats' downfall.

After putting to sea, the U-boats operated mostly on their own trying to find convoys in areas assigned to them by the High Command. If a convoy was found, the submarine did not attack immediately, but shadowed the convoy and radioed to the German Command to allow other submarines in the area to find the convoy. These were then grouped into a larger striking force and attacked the convoy simultaneously, preferably at night while surfaced to avoid the ASDIC.

In the first half of the War the submarines scored spectacular successes with these tactics, but were too few to have any decisive success. The attacks were made in the "Black Gap" between convoy escort areas and, when this was closed, off the coast of America. In the second half Germany had enough submarines, but this was more than nullified by equally increased numbers of convoy escorts, aircraft, and technical advances like radar and sonar. Huff-Duff and Ultra allowed the Allies to route convoys around wolf packs when they detected them from their radio transmissions.

Winston Churchill wrote that the U-boat threat was the only thing that ever gave him cause to doubt the Allies' eventual victory.

The Germans built some novel submarine designs, including the Type XVII, which used hydrogen peroxide in a Walther turbine (named for its designer, Dr Helmuth Walther) for propulsion. They also produced the Type XXII, which had a large battery and mechanical torpedo handling.

Italy had 116 submarines in service at the start of the war, with 24 different classes. They operated mainly in the Mediterranean but some were sent to a base at Bordeaux. A flotilla of several submarines operated out of the Eritrean colonial port of Massawa. The Italian design proved to be not very suitable for use in the Atlantic. The most interesting use of Italian boats was of midget submarines in attacks against shipping in the harbour at Gibraltar.

Japan had by far the most varied fleet of submarines of World War II, including manned torpedoes (Kaiten), midget submarines (Ko-hyoteki, Kairyu), medium-range submarines, purpose-built supply submarines (many for use by the Army), long-range fleet submarines (many of which carried an aircraft), submarines with the highest submerged speeds of the conflict (Sentaka I-200), and submarines that could carry multiple aircraft (WWII's largest submarine, the Sentoku I-400). These submarines were also equipped with the most advanced torpedo of the conflict, the oxygen-propelled Type 95 (what U.S. historian Samuel E. Morison postwar called "Long Lance").

Overall, despite their technical prowess, Japanese submarines, having been incorporated into the Imperial Navy's war plan of "Guerre D' Escadre" (Fleet Warfare), in contrast to Germany's war plan of "Guerre De Course", they were relatively unsuccessful. Being primarily used in the offensive roles against warships, which were fast, maneuverable and well-defended compared to merchant ships. In 1942, Japanese submarines sank two fleet aircraft carriers, one cruiser, and several destroyers and other warships, and damaged many others, including two battleships. They were not able to sustain these results afterward, as Allied fleets were reinforced and became better organized. By the end of the war, submarines were instead often used to transport supplies to island garrisons. During the war, Japan managed to sink about 1 million tons of merchant shipping (184 ships), compared to 1.5 million tons for Great Britain (493 ships), 4.65 million tons for the U.S. (1,079 ships) and 14.3 million tons for Germany (2,840 ships).

Early models were not very maneuverable under water, could not dive very deep, and lacked radar. (Later in the war units that were fitted with radar were in some instances sunk due to the ability of U.S. radar sets to detect their emissions. For example, Batfish (SS-310) sank three such equipped submarines in the span of four days). After the end of the conflict, several of Japan's most original submarines were sent to Hawaii for inspection in "Operation Road's End" (I-400, I-401, I-201 and I-203) before being scuttled by the U.S. Navy in 1946, when the Soviets demanded access to the submarines as well.

France had 112 submarine in service at the beginning of the war. They operated in the North Sea and off Norway. After the French-German Armistice, French submarines were required to return to France but many were commandeered by the British. The German capture of French submarine bases gave them freer access to the Atlantic.

There were 70 operational submarines in 1939. Two classes were selected for mass production, the seagoing "S class" and the ocean going "T class" as well as the coastal "U class". All were built in large numbers during the war. They operated off Norway during the German invasion as well as in the North Sea. In the Mediterranean they attacked Axis supplies to North Africa from their base in Malta. In addition British submarines attacked Japanese shipping in coastal waters during the Pacific campaign.

The Red Fleet had 144 submarines in service or under construction at the start of the war.

The U.S. used its submarines to attack merchant shipping (commerce raiding or guerre de course), in an effort to starve both Japanese Pacific island forces and the home islands, and to prevent imports of raw materials and oil.

Where Japan had the finest submarine torpedoes of the war, the USN had perhaps the worst, the Mark 14 steam torpedo, with a Mk 6 magnetic influence exploder designed to explode under the hull of the target vessel and a Mk 5 contact exploder, neither of which was reliable. For the first twenty months of the war, senior Submarine Force commanders (including RADM Ralph Christie, ComSouthWestPac, a key member of the Mk 6's design team) attributed the torpedo failures to poor approach and attack techniques by submarine commanders. The depth control mechanism of the Mark 14 (designed for an earlier slower-running torpedo) was corrected in August 1942, but field trials for the exploders were not even ordered until mid-1943, when tests in Hawaii and Australia confirmed the flaws.

The Mk 6 exploder was corrected by deactivating its magnetic influence mechanism and changing the firing pin of the contact exploder from one of high-friction steel to a less-friction alloy. The modifications were retro-fitted on torpedoes in service and incorporated into new production, after which the Mark 14 became a reliable weapon.

In September 1943 the Mark 18 electric torpedo was placed into service to provide a "wakeless" torpedo, but its range and speed were less than that of the Mark 14 and it had a smaller warhead. It too showed flaws that had not been corrected by testing: its battery produced hydrogen gas that could not be vented and it showed a disturbing tendency to "run circular" (that is, to travel in a circular path back to the firing submarine). The losses of the USS Tang and the USS Tullibee in 1944 resulted from self-inflicted hits by Mark 18 torpedoes fired from their stern tubes (which hit the submarines amidships), and the USS Wahoo may have been severely crippled by a circular hit on her bow before being bombed by aircraft.

During World War II 314 submarines served in the United States Navy. 111 boats were in commission on 7 December 1941, with 38 of these considered modern "fleet boats", and of that number, 23 were lost. 203 submarines from the Gato, Balao, and Tench classes were commissioned during the war, with 29 lost. In total the United States Navy lost 52 boats to all causes during hostilities, and 41 of the losses were directly attributable to enemy action. 3,506 submariners were killed or missing-in-action.

At first, Japanese anti-submarine defenses proved less than effective against U.S. submarines. Japanese sub-detection gear was not as advanced as that of some other nations. The primary Japanese anti-sub weapon for most of WWII was the depth charge. During the first part of the war, the Japanese tended to set their depth charges too shallow, and U.S. subs not trapped in shallow waters were frequently able to take advantage of depth gradient temperatures to escape from many attacks.

Historian Clay Blair claimed that Congressman Andrew J. May at a press conference held in June 1943 revealed the highly sensitive fact that American submarines had a high survival rate because Japanese depth charges were typically fuzed to explode at too shallow a depth. Various press associations sent this leaked news story over their wires and many newspapers (including one in Honolulu, Hawaii), published it.

Japanese naval forces heard of May's security breach and adjusted their depth charges to explode at a more effective depth. Vice Admiral Charles A. Lockwood, commander of the U.S. submarine fleet in the Pacific, later estimated that May's security breach cost the United States Navy as many as ten submarines and 800 crewmen killed in action.

Other historians claim that the May Incident never happened, and that the Japanese never discovered U.S. submarine depth capabilities during the war.

In addition to resetting their depth charges to deeper depths, Japanese anti-submarine forces also began employing auto-gyro aircraft and MAD (magnetic anomaly detection) equipment to sink U.S. subs, particularly those plying major shipping channels or operating near the home islands. Despite this onslaught, U.S. sub sinkings of Japanese shipping continue to increase at a furious rate as more U.S. subs deployed each month to the Pacific. By the end of the war, U.S. submarines had destroyed more Japanese shipping than all other weapons combined, including aircraft.

Operationally, two commands in the Pacific Theater, Submarines Pacific and Submarines Southwest Pacific, conducted 1,588 war patrols, resulting in the firing of 14,748 torpedoes and the sinking of 1,392 enemy vessels of a total tonnage of 5.3 million tons. Over 200 warships were sunk, including a battleship, 8 aircraft carriers of varying sizes, 11 cruisers, 38 destroyers, 25 submarines (including 2 U-Boats), and 70 other escort vessels. Submarines Pacific was assigned 51 boats in 1941; by the end of the war 169 boats were assigned. Monthly war patrols averaged 27 in 1942 and increased to 47 in 1945, with a high of 57 patrols dispatched in May 1945.

The first launch of a cruise missile (SSM-N-8 Regulus) from a submarine occurred in July 1953 from the deck of USS Tunny (SSG-282), a World War II fleet boat modified to carry this missile with a nuclear warhead. Tunny and her sister boat USS Barbero (SSG-317) were the United States's first nuclear deterrent patrol submarines. They were joined in 1958 by two purpose built Regulus submarines, USS Grayback (SSG-574), USS Growler (SSG-577), and, later, by the nuclear-powered USS Halibut (SSGN-587). So that no target would be left uncovered, four Regulus missiles had to be at sea at any given time. Thus, Barbero and Tunny, each of which carried two Regulus missiles, patrolled simultaneously. Growler and Grayback, with four missiles, or Halibut, with five, could patrol alone. These five submarines made 40 Regulus strategic deterrent patrols between October 1959 and July 1964.

In the 1950s, nuclear power partially replaced diesel-electric propulsion. The sailing of the first nuclear-powered submarine, the USN "Nautilus" in 1955 was soon followed by similar British, French and Russian boats. Equipment was also developed to extract oxygen from sea water. These two innovations, together with inertial navigation systems, gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as the crossing of the North Pole beneath the Arctic ice cap by the USS Nautilus in 1958. Most of the naval submarines built since that time in the United States and the Soviet Union and its successor state the Russian Federation have been powered by nuclear reactors. The limiting factors in submerged endurance for these vessels are food supply and crew morale in the space-limited submarine.

While the greater endurance and performance from nuclear reactors mean that nuclear submarines are better for long distance missions or the protection of a carrier battle-force, conventional diesel-electric submarines have continued to be produced by both nuclear and non-nuclear powers, as they can be made stealthier, except when required to run the diesel engine to recharge the ship's battery. Technological advances in sound dampening, noise isolation and cancellation have substantially eroded this advantage. Though far less capable regarding speed and weapons payload, conventional submarines are also cheaper to build. The introduction of air-independent propulsion boats led to increased sales numbers of such types of submarines.

In 1958 the USN carried out a series of trials with the USS Albacore. Various hull and control configurations were tested to reduce drag and so allow greater underwater speed and maneuverability. The results of these trials were incorporated into the Skipjack class and later submarines. From the same era is the first SSBN, the USS George Washington.

During the Cold War, the United States and the Soviet Union maintained large submarine fleets that engaged in cat-and-mouse games; this continues today, on a much-reduced scale. The Soviet Union suffered the loss of at least four submarines during this period: K-129 was lost in 1968 (which the CIA attempted to retrieve from the ocean floor with the Howard Hughes-designed ship named Glomar Explorer), K-8 in 1970, K -219 in 1986 (subject of the film Hostile Waters), and Komsomolets (the only Mike class submarine) in 1989 (which held a depth record among the military submarines -1000 m, or 1300 m according to the article K-278). Many other Soviet subs, such as K-19 (first Soviet nuclear submarine, and first Soviet sub at North Pole) were badly damaged by fire or radiation leaks. The United States lost two nuclear submarines during this time: USS Thresher and Scorpion. The Thresher was lost due to equipment failure, and the exact cause of the loss of the Scorpion is not known.

The sinking of PNS Ghazi in the Indo-Pakistani War of 1971 was the first submarine casualty in the South Asian region.

The United Kingdom employed nuclear-powered submarines against Argentina during the 1982 Falklands War; the sinking of the cruiser ARA General Belgrano by HMS Conqueror was the first sinking by a nuclear-powered submarine in war. During this conflict the conventional Argentinian submarine ARA Santa Fé was disabled by a Sea Skua missile, and the ARA San Luis claimed to have made unsuccessful attacks on the British fleet.

1903 - Simon Lake's submarine Protector surfaced through ice off Newport, Rhode Island.
1931 - Nautilus (ex. USS O-12) operated under ice near Spitsbergen.
1937 - Soviet submarine Krasnogvardeyets operated under ice in the Denmark Strait.
1941-45 - German U-boats operated under ice from the Barents Sea to the Laptev Sea.
1946 - USS Atule used upward-beamed fathometer in Operation Nanook in the Davis Strait.
1946-47 - USS Sennet used under-ice SONAR in Operation High Jump in the Antarctic.
1947 - USS Boarfish used upward-beamed echo sounder under pack ice in the Chukchi Sea.
1948 - USS Carp developed techniques for making vertical ascents and descents through polynyas in the Chukchi Sea.
1952 - USS Redfish used an expanded upward-beamed sounder array in the Beaufort Sea.
1957 - USS Nautilus reached 87 degrees north near Spitsbergen.
3 August 1958 - Nautilus used an inertial navigation system to reach the north pole.
17 March 1959 - USS Skate surfaced through the ice at the north pole.
1960 - USS Sargo transited 900 miles under ice over the shallow (125 to 180 feet deep) Bering-Chukchi shelf.
1960 - USS Seadragon transited the Northwest Passage under ice.
1962 - Soviet November-class submarine Leninskiy Komsomol reached the north pole.
1971 - HMS Dreadnought reached the north pole.
6 May 1986 - USS Ray, USS Hawkbill, and USS Archerfish, as part of LANTSUBICEX '86, surfaced together at the North Pole. First multi-submarine surfacing in history.
19 May 1987 - HMS Superb joined USS Billfish and USS Sea Devil at the North Pole. The first time British and Americans met at the North Pole.
March 2007 - USS Alexandria participated in the Joint U.S. Navy/Royal Navy Ice Exercise 2007 (ICEX-2007) in the Arctic Ocean with the Trafalgar-class submarine HMS Tireless.

Ballistic missile submarines (SSBNs or boomers in American slang) carry submarine-launched ballistic missiles (SLBM) with nuclear warheads, for attacking strategic targets such as cities or missile silos anywhere in the world. They are currently universally nuclear-powered, to provide the greatest stealth and endurance. (The first Soviet ballistic missile submarines were diesel-powered.) They played an important part in Cold War mutual deterrence, as both the United States and the Soviet Union had the credible ability to conduct a retaliatory strike against the other nation in the event of a first strike. This comprised an important part of the strategy of Mutual Assured Destruction.

The US has 18 Ohio-class submarines, of which 14 are Trident II SSBNs, each carrying 24 SLBMs. The American George Washington class "boomers" were named for famous Americans, and together with the Ethan Allen, Lafayette, James Madison, and Benjamin Franklin classes, these SSBNs comprised the Cold War-era "41 for Freedom." Later Ohio-class submarines were named for states (recognizing the increase in striking power and importance, equivalent to battleships), with the exception that SSBN-730 gained the name of a Senator. The first four Ohio-class vessels were equipped with Trident I, and have now been converted to carry Tomahawk guided missiles for land and shipping attack.

The Royal Navy possess a single class of four ballistic missile submarines (what RN call "bombers", for their function), the Vanguard class with Trident missiles. The Royal Navy's previous ballistic missile submarine class was the Resolution class, with Polaris missiles, which also consisted of four boats. The Resolutions, named after battleships to convey the fact they were the new capital ships, were decommissioned when the Vanguards entered service in the 1990s.

France operates a force de frappe, including a nuclear ballistic submarine fleet made up of one SSBN Redoutable class and three SSBNs of the Triomphant class. One additional SSBN of the Triomphant class is under construction.

The People's Republic of China's People's Liberation Army Navy's SLBM inventory is relatively new. China launched its first nuclear armed submarine in April 1981. The PLAN currently has 1 Xia class ("Type 92") at roughly 8,000 tons displacement. The Type 92 is equipped with 12 SLBM launching tubes. China's SLBM program is built around its JL-1 inventory. The Chinese Navy is estimated to have 24 JL-1s. The JL-1 is basically a modified DF-21.

The PLAN plans to replace its JL-1 with an unspecified number of the longer ranged, more modern JL-2s. Deployment on the JL-2 reportedly began in late 2003.

Attack submarines are fast, long range boats with torpedoes and cruise missiles to attack submarines, ships and land targets. They carry sonars, and other sensors, for target location and fire control systems for weapon launching.

In 1982 a study group was set up by the USN to define the requirements for a new SSN, later known as Seawolf. The submarine was commissioned in 1997. It had twice the weapon load of the Los Angeles class, with a new combat system (BSY-2) and new sonars. Unfortunately its cost proved unacceptable and so a more affordable design was started. This Virginia class had a reduced weapon load but with a wide variety of types.

The Royal Navy is building the Astute-class submarines as successors to its Swiftsure and Trafalgar classes. The first was launched in 2007.

The latest Chinese attack submarine class is the Type 093 (Shang), first launched in 2002, which is replacing the Type 091 (Han) class.

The Russian 949A (Oscar II) SSN was built from about 1989 to the late 90s. Older attack submarines have been decommissioned.

In Australia six Collins-class SSKs were built between 1996 and 2003, while Sweden has built three A19 SSKs.

The French Barracuda-class submarine is planned but will not replace its Rubis attack submarines until 2016.

These boats are lead-acid battery powered, being charged between runs from support facilities. They may have a surface speed of a few knots but generally their underwater speed is less than a knot. Their depth capabilities are often only a few metres. Some are capable of carrying over 50 passengers. They are found in the major tourist resorts in the warm water regions.

These can be used for a variety of purposes from scientific research, underwater filming and construction to search and salvage. They often can be fitted with a number of tools with lights, cameras, acoustic tracking and communications. They tend to be 2 or 3 person craft, sometimes with diver lockout facilities. Alternatively they can be simple craft used to aid divers.

Races are held in the David Taylor Model Basin in the U.S. over a 100 m course. The 9th races were held in 2007 at which 22 teams took part, with 26 submarines. A speed record of 8 knots was set for a two man submarine and 5 knots for a one man submarine.

Up to August 1914 there were 68 submarine accidents. There were 23 collisions, 7 battery gas explosions, 12 gasoline explosions, and 13 sinkings due to hull openings not being closed.

There have been a number of accidental sinkings but also some collisions between submarines. Examples of the former include the loss of HMS Affray in the English Channel in 1951 due to the snort mast fracturing, USS Thresher in 1963 due to a pipe weld failure during a test dive, however many other scenarios have been proven to be probable causes of sinking, most notably a battery malfunction causing a torpedo to detonate internally, and the loss of the Russian Kursk on 12 August 2000 probably due to a torpedo explosion. An example of the latter was the incident between the Russian K-276 and the USS Baton Rouge in February 1992.

Since submarines have been actively deployed, there have been several incidents involving submarines that were not part of major combat. Most of these incidents were during the Cold War, but some are more recent. Since the year 2000 there have been 9 major naval incidents involving submarines. There were three Russian submarine incidents, in two of which the submarines in question were lost, along with three United States submarine incidents, one Chinese incident, one Canadian, and one Australian incident. In August 2005, the Russian PRIZ, an AS-28 rescue submarine was trapped by cables and/or nets off of Petropavlovsk, and saved when a British ROV cut them free in a massive international effort.

Until the advent of nuclear marine propulsion, most 20th-century submarines used batteries for running underwater and gasoline (petrol) or diesel engines on the surface and to recharge the batteries. Early boats used gasoline but this quickly gave way to kerosene, then diesel, because of reduced flammability. Diesel-electric became the standard means of propulsion. Initially the diesel or gasoline engine and the electric motor were on the same shaft, which also drove a propeller with clutches between each of them. This allowed the engine to drive the electric motor as a generator to recharge the batteries and also propel the submarine if required. The clutch between the motor and the engine would be disengaged when the boat dived so that the motor could be used to turn the propeller. The motor could have more than one armature on the shaft-these would be electrically coupled in series for slow speed and parallel for high speed (known as "group down" and "group up" respectively).

In the 1930s the principle was modified for some submarine designs, particularly those of the U.S. Navy and the British U-class. The engine was no longer attached to the motor/propeller drive shaft but drove a separate generator, which would drive the motors on the surface and/or recharge the batteries. This diesel-electric propulsion allowed much more flexibility, for example the submarine could travel slowly whilst the engines were running at full power to recharge the batteries as quickly as possible, reducing time on the surface, or use its snorkel. Also it was now possible to insulate the noisy diesel engines from the pressure hull making the submarine quieter.

There were other power sources attempted—oil-fired steam turbines powered the British "K" class submarines built during the First World War and in following years but these were not very successful. This was selected to give them the necessary surface speed to keep up with the British battle fleet.

Steam power was resurrected in the 1950s with the advent of the nuclear-powered steam turbine driving a generator, which is now used in all large submarines. There was an attempt to use a very advanced lead cooled fast reactor on Project 705 "Lira" but it's maintenance was considered too expensive. By removing the requirement for atmospheric oxygen these submarines can stay submerged indefinitely so long as food supplies remain (air is recycled and fresh water distilled from seawater). These vessels always have a small battery and diesel engine/generator installation for emergency use when the reactors have to be shut down.

Anaerobic propulsion was employed by the first mechanically driven submarine Ictineo II in 1864. Ictineo's engine used a chemical mix containing a peroxide compound, that generated heat for steam propulsion while at the same time solved the problem of oxygen renovation in an hermetic container for breathing purposes. The system wasn't employed again until 1940 when the German Navy tested a system employing the same principles, the Walter turbine, on the experimental V-80 submarine and later on the naval U-791 submarine. At the end of the Second World War the British and Russians experimented with hydrogen peroxide/kerosene (paraffin) engines, which could be used both above and below the surface. The results were not encouraging enough for this technique to be adopted at the time, although the Russians deployed a class of submarines with this engine type code named Quebec by NATO, they were considered a failure. Today several navies, notably Sweden now use air-independent propulsion boats, which substitute liquid oxygen for hydrogen peroxide.

The German Type 212 submarine uses nine 34-kilowatt hydrogen fuel cell as air-independent propulsion, which makes it first series production submarine using fuel cell.

Most small modern commercial submarines that are not expected to operate independently use batteries that can be recharged by a mother-ship after every dive.

Towards the end of the 20th century, some submarines began to be fitted with pump-jet propulsors instead of propellers. Although these are heavier, more expensive, and often less efficient than a propeller, they are significantly quieter, giving an important tactical advantage.

A possible propulsion system for submarines is the magnetohydrodynamic drive, or "caterpillar drive", which has no moving parts. It was popularized in the movie version of The Hunt for Red October, written by Tom Clancy, which portrayed it as a virtually silent system. (In the book, a form of propulsor was used rather than an MHD.) Although some experimental surface ships have been built with this propulsion system, speeds have not been as high as those hoped. In addition, the noise created by bubbles, and the higher power settings a submarine's reactor would need, mean that it is unlikely to be considered for any military purpose.

Drebbel's 1620 submarine is thought to have incorporated floats with tubes to allow air down to the rowers. The steam powered submarines used to run with their hulls awash with air being taken down through their conning towers. During the First World War the British are believed to have experimented with a similar concept to the schnorkel, that is a mast through which air is drawn.

Diesel submarines needed air to run their engines, and so carried very large batteries for submerged travel. These limited the speed and range of the submarines while submerged. The schnorchel (used by prewar Dutch submarines) was used after 1943 to allow German submarines to run just under the surface, attempting to avoid detection visually and by radar. After the war the concept became widely used and the term was anglicised to "shnorkel" or "snorkel" in English. The German navy also experimented with engines that would use hydrogen peroxide to allow diesel fuel to be used while submerged, but technical difficulties were great.

Originally submarines were navigated using a porthole but the periscope was introduced by World War I. Passive sonar was introduced in submarines during the First World War but active sonar ASDIC did not come into service until the inter-war period. Today the submarine may have a wide variety of sonar arrays, from bow mounted to trailing ones. There are often upward-looking under-ice sonars as well as depth sounders.

Radar came in during the 1930s, with radar warning receivers in the Second World War.

Originally the submarine's torpedoes were aimed by pointing the boat in the correct direction. This was determined from the targets course and speed by measurements of angle and range via the periscope. The necessary calculation was first carried out manually and later by mechanical calculators. Today it is achieved by digital computers with display screens providing all necessary information on the torpedo status and ship status.

Early submarines carried torpedoes externally and then internally. In the latter case both bow mounted and stern mounted tubes were used but today only the former are still employed. Some specialised mine laying submarines were built. The modern submarine is capable of firing many types of weapon from its launch tubes, including UAVs.

Up until the end of WW2 it was common to fit deck guns to submarines to allow them to sink ships without wasting torpedoes.

German submarines in World War II had rubber coatings and could launch chemical devices to provide a decoy when the boat was under attack. These proved to be not very effective as sonar operators came to distinguish between the decoy and the submarine. Modern submarines can launch a variety of devices for the same purpose, as well as having coatings.

Wireless was used to provide communication to and from submarines in the First World War. With time the type, range and bandwidth of the communications systems have increased. Because of the danger of intercept, transmissions by a submarine are minimised. Various periscope mounted aerials have been developed to allow communication without surfacing.

The standard navigation system for early submarines was by eye, with use of a compass. The gyrocompass was introduced in the early part of the 20th century and inertial navigation in the 1950s. The use of satellite based navigation is of limited use to submarines, except at periscope depth or when surfaced.

After the sinking of the A1 submarine in 1904, lifting eyes were fitted to British submarines and in 1908 air-locks and escape helmets were provided. The RN experimented with various types of escape apparatus but it was not until 1924 that the "Davis Submerged Escape Apparatus" came in. The USN used the similar "Momsen Lung". The French used "Joubert's apparatus" and the Germans used "Draeger's apparatus".

Rescue submarines for evacuating a disabled submarine's crew came in the 1970s and the British unmanned vehicle was used for recovering an entangled Russian submarine crew in 2005. A new NATO Submarine Rescue System entered service in 2007.