The Pluviôse class were built as part of the French Navy's 1905 building program to a double-hull design by Maxime Laubeuf.

The other launchers were a rotating pair of Drzewiecki drop collars in a single mount positioned on top of the hull at the stern.

[6] Both submarines suffered damage, particularly Watt, which sustained a gash over 40 centimetres (16 in) in length in her external port ballast tank that required a substantial period of time to repair.

After the declaration of war, Watt conducted patrols in the English Channel, and from September 1914 to June 1915 she was based in England at Portsmouth as part of defense agreements between France and the United Kingdom.

At daybreak on 26 March 1918, she was on the surface in the Mediterranean Sea north of the Galite Islands off the coast of Tunisia when she crossed paths with an Allied convoy en route from Gibraltar to Bizerte, Tunisia, consisting of 15 ships escorted by the British Royal Navy warship HMS Jeannette II, the United States Navy armed yacht USS Wenonah, the U.S. Navy gunboat USS Nashville, and two French naval trawlers.

Watt submerged, and Jeannette II attacked her, dropping two depth charges and forcing her back to the surface.

Wenonah fired twelve rounds, inflicting considerable damage on Watt, killing her commanding officer and wounding five others.

[6][10] A joint court of inquiry with one American, two British, and two French naval officers as members took place at Gibraltar and found no one to blame for the incident.

Another joint court of inquiry consisting of two British and two French naval officers took place at Bizerte, and also found no one to blame, concluding that Watt had disobeyed orders governing submarines operating in the area.