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

Ordered in 1926 under Naval Program 75,[1] Diane was laid down at Chantiers et Ateliers Augustin Normand in Le Havre, France, on 25 April 1927.

[1] When the British warships opened fire on the French ships in the harbor at 17:57,[1] beginning their attack on Mers-el-Kébir, Diane was 3.5 nautical miles (6.5 km; 4.0 mi) west of Pointe de l’Aiguille (35°52′31″N 000°29′04″W / 35.87528°N 0.48444°W / 35.87528; -0.48444 (Pointe de l’Aiguille)) in Oran Province.

[1] As Operation Catapult continued, British forces attacked the French squadron at Dakar in Senegal on 8 July 1940.

[3][5] Receiving word of the attack, French naval authorities at Oran ordered Eurydice, Ariane, and Diane to form a patrol line off Cape Falcon, Algeria.

[1] Diane still was in her unarmed and unfueled status at Oran when Allied forces invaded French North Africa in Operation Torch on 8 November 1942.