He fought in the European theatre of World War II, attaining the rank of captain before retiring from the army in 1947, and starting his career as a historian around 1979.

Delaforce attended Winchester College, and spent a year finishing his education at Queen's University Belfast before enlisting in the British Army in 1942.

[3] Delaforce attended an Officer Cadet Training Unit in Catterick, North Yorkshire, and was commissioned into the Suffolk Yeomanry.

[4] In the Netherlands, he became a forward observation officer, and was injured, having his ribs and one arm broken, and his leg paralysed when his Universal Carrier was hit by an anti-tank mine.

[6] In 1958, he joined Intam Limited, a subsidiary of the London Press Exchange, and by 1961, he was vice president and general manager of Otto-Intam, a New York-based advertising agency.