In anticipation of an Italian declaration of war, the , including "Le Terrible", assembled in Mers-el-Kébir, French Algeria, on 5–9 April, only to return to Brest when the Germans invaded Norway on the 10th. The ship returned to Mers-el-Kébir together with the bulk of the on 27 April. She took part in a sortie by the into the Western Mediterranean on 12–13 June, after Italy declared war on the Allies on the 10th. "Le Terrible" was in Mers-el-Kébir when the British attacked the ships there, hoping to deny them to the Germans, on 3 July. She exited the harbor and engaged British destroyers as she escorted "Strasbourg" back to Toulon.