They were essentially experimental submarines, and although in service during World War I, saw no action.

The class was designed by Maxime Laubeuf and used Drzewiecki drop collar launchers and external cradles to launch torpedoes.

The submarines had a surfaced displacement of 178 long tons (181 tonnes) and a submerged displacement of 253 long tons (257 t).

They had a single shaft powered by one diesel engine for surface running of 150 hp (112 kW) and an electric motor which produced 130 horsepower (97 kilowatts) for submerged propulsion.

The maximum speed was 9.3 knots (17.2 kilometres per hour; 10.7 miles per hour) on the surface and 6.2 knots (11.5 km/h; 7.1 mph) while submerged with a surfaced range of 1,300 nautical miles (2,400 kilometres; 1,500 miles) at 8 knots (15 km/h) and a submerged range of 65 nautical miles (120 km) at 3.8 knots (7.0 km/h).