Dundee-based submarines of the Royal Navy's 2nd flotilla were patrolling the North Sea when the second world war broke out in 1939. From 1940 they were joined by submarines from enemy-occupied France, Holland, Norway and Poland to form a unique international force, the 9th Submarine Flotilla. Russian submarines were also based in Dundee in 1944.
A memorial to the submariners is located at the north eastern end of Victoria Dock near the Clocktower warehouse and can be accessed from Camperdown Street.