The American inventor, David Bushnell, began experimenting with the idea of producing a ship that could travel underwater in the latter years of the eighteenth-century. Attempts were also made to produce submarines during the American Civil War.

The first Royal Navy submarine was developed by John P. Holland and was launched in 1902. At this time France led the world in the design and construction of steam-powered underwater boats. However, after 1905, Germany began to develop a submarine with real fighting qualities. In 1913 Germany produced its first diesel-powered Unterseeboot (U-boat).

By the outbreak of the First World War Germany had 10 diesel-powered U-boats (17 more under construction). The German Navy also had 30 petrol-powered submarines. Britain had 55 submarines whereas the French had 77. Although submarines were slow, fragile and able to dive for only a couple of hours at a time, with torpedoes they posed a serious threat to other ships.

Submarines during the war had four torpedo tubes in the bow and one or two in the stern, with 16 cm guns and mine-laying equipment. The diving depth was 30 to 75 metres, the surface speed was 18 knots, and when submerged 7.5 to 8.5 knots. The size of the crew numbered between 20 to 40.

During the First World War Britain lost 54 submarines but by 1918 had 137 in service with another 78 under construction. The German Navy had 134 operational U-boats and these managed to sink 192 boats, killing more than 5,400 people.