The Type IX U-boat was designed by Nazi Germany's Kriegsmarine in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern United States in an attempt to disrupt the stream of troops and supplies bound for Europe. It was derived from the Type IA, and appeared in various sub-types.
The V and W class was an amalgam of six similar classes of destroyer built for the Royal Navy under the 9th, 10th, 13th and 14th of fourteen War Emergency Programmes during the First World War and generally treated as one class. For their time they were among the most powerful and advanced ships of their type in the world, and set the trend for future British designs.
The Loch class was a class of anti-submarine (A/S) frigate built for the Royal Navy and her Allies during World War II. They were an innovative design based on the experience of three years of fighting in the Battle of the Atlantic and attendant technological advances. Some shipyards had trouble building these larger ships, which led to widespread use of the Castle-class corvette, introduced around the same time.
Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one of the world's most varied and powerful submarine fleets.
At the outbreak of the Second World War Nazi Germany's Kriegsmarine had 21 destroyers in service, while another one was just being completed. These 22 vessels – comprising 3 classes – had all been built in the 1930s, making them modern vessels. Including that final pre-war vessel, a further 19 were brought into service during the war and more were captured from opposing navies, including the Italian Navy after the Italian Armistice with the Allies in 1943.
A merchant submarine is a type of submarine intended for trade, and being without armaments, it is not considered a warship like most other types of submarines. The intended use would be blockade running, or to dive under Arctic ice.
The Italian auxiliary cruiser Ramb II was a pre-war banana boat built at Monfalcone by the CRDA in 1937. She briefly served as an auxiliary cruiser with Regia Marina early in World War II before becoming an auxiliary transport with the Imperial Japanese Navy later in her career.
The Redoutable-class submarines were a group of 31 submarines built between 1924 and 1937 for the French Navy. Most of the class saw service during the Second World War. The class is also known in French as the Classe 1 500 tonnes, and they were designated as "First Class submarines", or "large submarine cruisers". They are known as the Redoutable class in reference to the lead boat Redoutable, in service from 1931 to 1942. The class is divided into two sub-class series, Type I, known as Le Redoutable and Type II, Pascal.
The Cagni or Ammiraglio Cagni class was a class of submarines built for Italy's Regia Marina during World War II.
U-230 was a Type VIIC U-boat built for Nazi Germany's navy (Kriegsmarine) for service during World War II.
Italian submarine Luigi Torelli was a Marconi-class submarine of the Italian navy during World War II. The vessel operated in the Atlantic from September 1940 until mid-1943, then was sent to the Far East. After Italy's surrender in 1943, the Luigi Torelli was taken over by Nazi Germany's Kriegsmarine, then, in the waning months of the war, the Japanese Imperial Navy. It was one of only two ships to serve in all three major Axis navies, the other being the Italian submarine Comandante Cappellini.
The Élan class was a class of French minesweeping sloops. Originally designed as minesweepers, they were never used in that role, instead being used mostly as escort vessels. Built between 1936 and 1940, the first came into service just before the outbreak of World War II.
German submarine U-476 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.
The Chamois class were French minesweeping sloops ordered between 1935 and 1939. They were similar in design to the Élan class, and like them classed as minesweepers, but were actually used as anti-submarine ships, convoy escorts and patrol vessels.
Sava was a Flutto-class submarine in service with the Yugoslav Navy. Built by Cantieri Riuniti dell'Adriatico in Monfalcone during the Second World War, Sava was laid down and completed as Nautilo for service with the Italian Regia Marina.
The German torpedo boat TA37 was an Ariete-class torpedo boat operated by the German Kriegsmarine during the Second World War. The ship was built for the Italian Navy by the shipbuilder CRDA at their Trieste shipyard with the name Gladio in 1943, but was incomplete when Italy surrendered to the Allies in September 1943, and was seized by Nazi Germany. The ship entered service as TA37 in 1944, serving in the Adriatic and Aegean seas and was sunk by British destroyers on 7 October 1944.
Regia Marina 
