Complex sentence: Promoted to captain in September 1942, Graham briefly served on the headquarters of the 1st Armoured Division before being attached to the British Army in the North Africa and Italy, including service with the British 7th Armoured Division in 1943--1944.
Split into simpler sentences: Promoted to captain in September 1942, Graham briefly served on the headquarters of the 1st Armoured Division before being attached to the British Army. Serving with the British 7th Armoured Division, he saw action with them in the North Africa and Italy 1943--1944.