[7] He served with distinction during the First World War, earning the Military Cross (MC) in 1915, the Distinguished Service Order (DSO) in 1918,[8] and was five times mentioned in despatches.

[6] As a brigadier, a rank he had been promoted to in April 1937,[9] he served on the General Staff in the headquarters of Northern Command from 1937 and was promoted to major general in September 1938 (with seniority backdated to 9 January 1938)[10] and soon after was appointed Commander of British Troops in China in 1938.

[6][11] Grasett served in the Second World War as General Officer Commanding (GOC) of the 48th (South Midland) Division from 1941 and, promoted to acting lieutenant general on 7 November 1941,[12] was made GOC of VIII Corps on the south coast of England from November 1941.

[6] He was appointed Lieutenant Governor of Jersey[6][14] and Colonel Commandant of the Royal Engineers in 1945 and retired from the army in 1947.

[6] In 1935, Grasett married Joan Mary, who was the daughter of JK Foster of Egton Manor, Yorkshire.