Captain Trumbull Warren and Field Marshal the Viscount Bernard L. Montgomery of Alamein in front of staff car in England, January 1942. Captain Warren was aide-de-camp to Montgomery in North Africa. Following the decisive battle at El-Alamein and the routing from North Africa of the German army under Field Marshal Rommel, Montgomery returned to England, prior to his assignment for the landings in Sicily in July 43 and the initial stages of the Italian campaign. Warren would return to Canada to Royal Military College to take the War Staff course before returning to the UK. He would join Montgomery again in Italy as Personal Assistant a position he maintained to the end of the war.

Battles of El-Alamein, fought from July 1–27 and October 23—November 11, 1942, pitted German and Italian forces against British, Australian, New Zealander, South African, and Indian forces in coastal central Egypt and resulting in a pivotal Allied victory. After the First Battle of El-Alamein in Egypt (150 miles west of Cairo), ended in a stalemate, the second one was decisive. It marked the beginning of the end for the Axis in North Africa. Field Marshal Erwin Rommel was comprehensively defeated by the British Eighth Army, and Allied material superiority meant that he had little chance of rallying his broken forces.