Ordered on 4 May 1936, "Casque" was laid down by Forges et Chantiers de la Méditerranée at their shipyard in La Seyne-sur-Mer on 30 November 1936. She was launched on 2 November 1938 and entered service on 20 June 1940. That day the ship steamed for Oran, French Algeria. After the British attacked French Navy ships in nearby Mers-el-Kébir on 3 July, "Casque" joined the other destroyers in Oran in leaving that day for a safer port, but she had to return to Oran because she had damaged her propeller while getting underway. After repairs, the ship rendezvoused with her sister and they reached Toulon on 7 July, at which time she was immediately placed in reserve.