Crocker's I Corps was to form part of the British Second Army, then under his former army commander in North Africa, Lieutenant-General Sir Kenneth Anderson (but replaced in January 1944 by Lieutenant-General Miles Dempsey), training for Operation Overlord, the Allied invasion of Northern France. Crocker was to aided throughout by his BGS, Philip Balfour. Despite Crocker's background in armoured warfare, I Corps was predominantly an infantry formation, but General Sir Bernard Montgomery, Allied Land Forces Commander for D Day and the battle of Normandy 21st Army Group, had confidence in Crocker's organisational skills and assigned I Corps the difficult task of capturing the city of Caen. For the landings I Corps had under command the 3rd Canadian Division, supported by the 2nd Canadian Armoured Brigade, and Major-General Tom Rennie's British 3rd Division, supported by the 27th Armoured Brigade, and Major-General Richard Gale's 6th Airborne Division. On D-Day, 6 June 1944, Crocker had a larger task than any other Allied corps commander: he had to control two landing beaches (Juno and Sword) and an airborne assault. The fact that, in spite of inevitable mishaps, the landings went so well was a testimony to Crocker's planning.