In October 1914, after the start of World War I, the British Admiralty ordered ten submarines to design 602E, to be built by Canadian Vickers in Montreal, Quebec.

Another ten submarines were secretly constructed at Fore River Yard at Quincy, Massachusetts, in the then neutral United States.

A third group, of twenty-five British H-class subs, was constructed in 1917-1919 in Britain, many of them serving in World War II.

In 1917 the Imperial Russian Navy ordered a total of 17 submarines for its Baltic and Black Sea Fleets.

They were then disassembled, taken by ship to Vladivostok, by the Trans-Siberian Railroad to Saint Petersburg and Nikolayev to be reassembled in Russian shipyards.