During World War II, she operated on the Allied side until 1940, when she became part of the naval forces of Vichy France.

Amphitrite was authorized in the 1927 naval program[1] and her keel was laid down at Chantiers et Ateliers Augustin Normand in Le Havre, France, on 8 August 1928.

[1][2] When World War II began on 1 September 1939 with the German invasion of Poland, Amphitrite was part of the 18th Submarine Division — a part of the 2nd Submarine Squadron in the 6th Squadron — along with her sister ships Méduse, Oréade, and La Psyché, based at Oran in Algeria.

The attack on Mers-el-Kébir — in which a British Royal Navy squadron attacked a French Navy squadron moored at the naval base at Mers El Kébir on the coast of Algeria near Oran — took place on 3 July 1940, and that day Amphitrite and her sister ships Amazone and Méduse put to sea to establish a defensive patrol line along a 20-nautical-mile (37 km; 23 mi) radius from Casablanca.

On 24 September 1940, Amphitrite, Amazone, Antiope, and Sibylle received orders to deploy to French West Africa.

[1] Amphitrite got underway from Casablanca on 25 September 1940,[1] the day Operation Menace ended in the withdrawal of the British and Free French forces from Dakar.

[1] Amphitrite was in port at Casablanca on 8 November 1942 when Allied forces invaded French North Africa in Operation Torch.

[1] Amphitrite suffered additional damage as the U.S. Navy battleship USS Massachusetts (BB-59) and her accompanying cruisers and destroyers shelled the harbor at Casablanca during the day.