After World War I France had a fleet of 36 submarines, in a variety of classes, plus 11 ex-German U-boats; these were mostly obsolete (all had been disposed of by the 1930s) and she was interested in replacing them.
At the same time, the major powers were negotiating an arms limitation treaty at the 1922 Washington Naval Conference.
There was discussion of banning submarines altogether, and to outlaw their use (a course favoured by Britain) both France and Italy opposed this.
And further enlarged design, the Phenix class, were ordered but not built, due to France's defeat in 1940 and the subsequent armistice.
They also emphasized habitability, needing to be suitable for service in France's colonial empire, which could mean long voyages and operations in the tropics.
One submarine had been sunk in action, and several others scuttled to prevent their capture; seven others, in British ports at the time of the armistice, became part of the Free French naval force (FNFL).
In November 1942, with the invasion of Vichy territory by the Germans, many of the remaining vessels were scuttled, or captured by the Axis.
Those that survived, or managed to escape, joined the FNFL; despite losses, and with replacement from allied navies, France ended the war with 20 submarines in service, having lost 50 boats from a variety of causes.