The value of the small submersible in anti-blockade operations had been demonstrated in Europe as early as 1850–51, when the mere rumour of Wilhelm Bauer’s Brandtaucher was sufficient to cause a temporary relaxation of the Danish blockade of Kiel. Brandtaucher, a slab-sided iron coffin some 26ft (7.9m) long, displacing 38.5 tons (39.1 tonnes), and hand-cranked by two men, was armed with crude “limpet” charges which the crew were to fix to enemy hulls with leather “gloves” protruding from the craft’s hull.
Brandtaucher sank on trials and Bauer moved to Russia, where his later designs may have influenced the inventor Alexandrowski, whose submersible of 1868 utilized an engine driven by compressed air. Stepan Drzewiecki’s Podascophe, built at St Petersburg in 1876, returned to man-power for propulsion; but this 16ft (4.9m), two-man boat incorporated such notable features as a periscope, an adjustable screw and a caustic-soda air purifier.
Podascophe was armed with mines which were to be carried on the casing and released when the submersible lay beneath enemy ships. The Tsar’s navy ordered 52 boats of Drzewiecki’s design, but their fate is obscure. However, in September 1904 the Russian Navy is said to have contemplated a suicidal attack on Japanese warships blockading Port Arthur, with a two-man submersible in which an automobile engine replaced the bicycle-type pedals of Drzewiecki’s midgets. In 1902–03 the Russians had bought five examples of the American inventor Simon Lake’s Protector (which cannot be classified as a midget) and were experimenting with a Spanish-designed, German-built, 17 ton (17.3 tonne) midget called Forelj, which they planned to use against an anticipated Japanese attack on Vladivostock.