[1] In 1916, during World War I, Cazenove passed out of Sandhurst[2] and was commissioned as a second lieutenant into the Coldstream Guards, in which he served on the Western Front in 1917–18.

In September 1939, during World War II, the battalion, part of the 7th Guards Brigade of the 3rd Infantry Division, under Major-General Bernard Montgomery, was sent to France to join the British Expeditionary Force (BEF).

During the German invasion of France and Belgium in May 1940, the battalion fought in the delaying actions along the Ypres-Comines Canal and was then evacuated from Dunkirk.

In December 1942 the 73rd Brigade lost its infantry battalions and was simply designated Cornwall Coastal Area.

[9] For his war service, Cazenove had been mentioned in despatches, awarded the American Legion of Merit, and made a Commander of the Order of Orange-Nassau.