In July 1940, after the French surrender, she joined Admiral René-Émile Godfroy's Force X at Alexandria, Egypt; there, she was disarmed by agreement between the British and French admirals during Operation Catapult and interned by the British from 22 June 1940. Axis forces occupying the so-called Free Zone in November 1942 made Armistice terms between France and the Third Reich moot, and "Duguay-Trouin" rejoined the Allies on 30 May 1943. She was re-armed in July, and after modernisation in Casablanca and Oran, she returned to active service in September 1943. During her refit, "Duguay-Trouin" had her torpedo tubes and aircraft removed, and instead gained 4 75-millimetre AA guns, 15 20-millimetre guns and 10 13.2-millimetre machine guns.