WSubmarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, mine warfare and mine countermeasures.
WThe Mediterranean U-boat Campaign in the Mediterranean Sea was fought by Austria-Hungary and German Empire against the Allies during World War I. It was characterised by the ability of the Central Powers to raid with near impunity during the first years of the war, causing substantial shipping losses, until the introduction of the convoy system allowed the Allies to drastically cut their losses from 1917 on.
WThe Nyon Conference was a diplomatic conference held in Nyon, Switzerland, in September 1937 to address attacks on international shipping in the Mediterranean Sea during the Spanish Civil War. The conference was convened in part because Italy had been carrying out unrestricted submarine warfare, although the final conference agreement did not accuse Italy directly; instead, the attacks were referred to as "piracy" by an unidentified body. Italy was not officially at war, nor did any submarine identify itself. The conference was designed to strengthen non-intervention in the Spanish Civil War. The United Kingdom and France led the conference, which was also attended by Bulgaria, Egypt, Greece, Romania, Turkey, the Soviet Union and Yugoslavia.
WPassive Underwater Fire Control Feasibility System (PUFFS) was a passive sonar system for submarines. It was designated AN/BQG-4 and was primarily installed on United States Navy conventional submarines built in the 1950s beginning with the Tang class, and also those converted to GUPPY III or otherwise modernized in the 1960s. It was also equipped on the nuclear-powered USS Tullibee (SSN-597). It was also installed on the USS Thomas Edison (SSBN610) but never achieved operational status. Its transducers can be seen on pictures of the vessel. A version known as "Micropuffs" was fitted on Oberon-class submarines for the Royal Australian Navy, and as Type 2041 on the Upholder-class for the British Royal Navy. This class still serves in the Royal Canadian Navy as the Victoria class, where Micropuffs is known as BQG-501. The system was notable for three tall, fin-like domes topside, except on Micropuffs installations. The system was retained on several submarines transferred by the US to foreign navies. It was associated with long-range passive detection of targets for the Mark 45 nuclear torpedo and other weapons. Most submarines backfitted with it were also lengthened 12-16 feet to accommodate additional electronics and plotting rooms. It was also planned for Thresher and Sturgeon class nuclear submarines, but was not fitted on them except Micropuffs experimentally on Barb and Haddock. With the exception of the four Canadian Victoria-class submarines, all PUFFS-equipped submarines have been disposed of or preserved as museum ships.
WSonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels. Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics.
WThe U-boat Campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It took place largely in the seas around the British Isles and in the Mediterranean. The German Empire relied on imports for food and domestic food production and the United Kingdom relied heavily on imports to feed its population, and both required raw materials to supply their war industry; the powers aimed, therefore, to blockade one another. The British had the Royal Navy which was superior in numbers and could operate on most of the world's oceans because of the British Empire, whereas the Imperial German Navy surface fleet was mainly restricted to the German Bight, and used commerce raiders and unrestricted submarine warfare to operate elsewhere.
WUnrestricted submarine warfare is a type of naval warfare in which submarines sink vessels such as freighters and tankers without warning, as opposed to attacks per prize rules.