In the 19th century torpedoes were launched from surface "torpedo boats" but these were susceptible to gunfire as they had to close to a short range to launch. There was a requirement for a "submarine torpedo boat" which was shortened to "submarine".
The concept of an underwater boat has roots deep in antiquity. Although there are images of men using hollow reeds to breath 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 Peloponesian 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.
However, in the modern era, the first person to propose a submarine was the Englishman William Bourne who designed a prototype submarine in 1578. Unfortunately for him 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 means of 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:-
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.
On October 1, 1720, the Ottoman dockyard architect Ibrahim Efendi invented a submarine called the tahtelbahir. The Ottoman writer Seyyid Vehbi, in his Surname-i-Humayun, compared this submarine to an alligator. He recorded that during the circumcision ceremony for Sultan Ahmed III's sons, "the alligator-like submarine slowly emerged on the water and moved slowly to the sultan, and after staying on the sea for half an hour, submerged in the sea again to the great surprise of the public; then emerged one hour later, with five people walking outside the mouth of this alligator-like submarine, with trays of rice and zerde (a dish of sweetened rice) on their heads." He explained the technical information concerning the submarine "submerging in the sea and the crew being able to breath through pipes while under the sea".
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, 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.
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 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 one of its financiers, Horace Lawson Hunley) . The first Confederate submarine was the 30-foot long 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 the North's ships, which were blockading the South's 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.
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 first combustion-powered submarine was the steam and peroxide driven Ictineo II, launched in 1867 by Narcís Monturiol. It was originally launched in 1864 as a human-powered submarine, propelled by 16 men.
The 14 meter long craft was designed to carry a crew of two, dive 30 metres (96 ft), and demonstrated dives of two hours. When on the surface it ran on a steam engine, but underwater such an engine would quickly consume the submarine's oxygen. So Monturiol turned to chemistry to invent an engine that ran on a reaction of potassium chlorate, zinc, and manganese peroxide. The beauty of this method was that the reaction which drove the screw released oxygen, which when treated was used in the hull for the crew and also fed an auxiliary steam engine that helped propel the craft under water. In spite of successful demonstrations in the Port of Barcelona, Monturiol was unable to interest the Spanish navy, or the navy of any other country.
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 Russian government. In 1884 the same inventor built an electric-powered submarine.
Discussions between George Garret and Swede Thorsten Nordenfelt led to a series of steam powered submarines. The first was the Nordenfelt I, a 56 tonne, 19.5 metre long spindle shaped vessel similar to the Resurgam II, with a range of 240 kilometres and armed with a single external torpedo, completed in 1885. Greece, fearful of the return of the Ottomans, purchased it. Nordenfelt then built at Chertsey the Nordenfelt II (Abdülhamid) in 1886 and Nordenfelt III (Abdülmecid) in 1887, a pair of 30 metre long submarines with twin torpedo tubes, for a worried Ottoman navy. "[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 worried 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, and a hull shape and propeller and cruciform external controls anticipating later designs. Its underwater speed was ten knots, but it suffered from the short range of battery powered systems. 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. The Spanish Navy scrapped the project.
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 things 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 coming World War I.
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, 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 SS-1. A proto-type 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 proto-type (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 of New Jersey. In 1902, Holland received 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 Japan as Japan commissioned five Holland Type VII submarines into the Imperial Japanese Navy circa 1905. (Mr. Holland was no longer in control of his company at this point - as others were formally engauged in transactions with many other foreign nations around the world at this time). The Type VII design was adopted by the Royal Navy as well (with Holland's input, as the Holland class submarine, including Britain's Holland #1). The Imperial Japanese Navy purchased five similar designs in 1904 and were built and completed by the summer of 1905. Those submarines (in particular) were developed by an American shipbuilder working at the Fore River Ship and Engine Company in Quincy, Massachusett's. The man who superintended these first five (IJN) submarines at this Quincy shipyard (in the United States) was naval architect, Arthur L. Busch.
Commissioned in June 1900, the French steam and electric submarine Narval introduced the classic twin-hull design, with an inner hull inside an outer hull. France was "undoubtedly the first navy to have an effective submarine force" (Conway Marine "Steam, Steel and Shellfire"). These 200 tons ships had a range of over 100 miles on the surface, and over 10 miles underwater. The French submarine Aigette in 1904 further improved the concept by using a diesel rather than a gasoline engine for surface power. Large numbers of these submarines were built, with seventy-six completed before 1914.
A small submarine was launched by the Russians in 1902 and an improved version in 1903. Two American built submarines and a German one were sent to Vladivostok in 1904 but did not achieve anything in the war against Japan. Professor Bubnov developed several ingeneous designs while further foreign ones were bought. The Baltic fleet had 17 boats in 1908.
The first German submarine, the Forelle, was not built until 1903 by Krupp and sold to Russia. The first boat for the German Navy was completed in 1905. The French Aigette submarine was the first to have a diesel engine.
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 First Battle of the Atlantic. 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.
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.
Germany put submarines to devastating effect in the Second Battle of the Atlantic in World War II, 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 USA. 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 "wolf packs", (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.
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 afterwards, 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 US (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 US radar sets to detect their emissions. For example, Batfish (SS-310) sunk 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.
The US 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 in order to escape from many attacks.
Unfortunately, the deficiencies of Japanese depth-charge tactics were revealed in a June 1943 press conference held by U.S. Congressman Andrew J. May, a member of the House Military Affairs Committee who had visited the Pacific theater and received many confidential intelligence and operational briefings. At the press conference, May revealed that American submarines had a high survivability because Japanese depth charges were fused to explode at too shallow a depth, typically 100 feet (because Japanese forces believed U.S. subs did not normally exceed this depth). Various press associations sent this story over their wires, and many newspapers, including one in Honolulu, thoughtlessly published it. Soon enemy depth charges were rearmed to explode at a more effective depth of 250 feet. Vice Admiral Charles A. Lockwood, commander of the U.S. submarine fleet in the Pacific, later estimated that May's revelation cost the navy as many as ten submarines and 800 crewmen.
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.
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 configuarations were tested to reduce drag and so allow greater underwater speed and manoevreability. The results of these trials were incorporated into the Skipjack class and later submarines. The first SSBN was 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—1000m, 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 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 Argeninian submarine "Santa Fé" was disabled by a Sea Skua missile but the "San Luis" claimed to have made unsuccessful attacks on the British fleet.
The U.S. 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 are now being 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.
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 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.
Since submarines have been actively deployed, there have been several incidents involving submarines which 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.
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.
Most small modern commercial submarines which are not expected to operate independently use batteries which 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.
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". 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.
Radar came in during the 1930s, with radar warning receivers in the Second World War.
German submarines in World War II had rubber coatinds 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.
Rescue submarines for evacuating a disabled submarine's crew came in 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.