Pre-war activities included being stationed in Saigon (now Ho Chi Minh City), French Indochina for two months from January 1938.

[3] At the start of the war, now assigned to the 2nd Squadron of the Force de Raid,[4] she performed Atlantic patrols and convoy escort duties[5] and swept for the German battleships Scharnhorst and Gneisenau after they had sunk the British Armed Merchant Cruiser HMS Rawalpindi.

[9] Recalled to the Force de Raid in May,[10] Montcalm was then moved to Algiers in North Africa[11][12] where she stayed, performing at least one convoy escort,[13] until the Destruction of the French Fleet at Mers-el-Kebir, when she was ordered to Toulon.

Montcalm was refitted at Philadelphia, from February until August 1943, the engines were overhauled, aircraft installations removed and the French light anti-aircraft weapons were replaced and augmented.

She was allocated to the Western Task Force and supported Allied landings in Normandy at Omaha Beach in June 1944[19] and southern France in August.