General Sir Ashton Gerard Oswald Mosley Mayne, GCB, CBE, DSO (24 April 1889 – 17 December 1955) was a senior British Indian Army officer active in both the First World War and Second World War, where he commanded Eastern Command, India.

He saw action against the Mohmands and the Swatis on the North West Frontier between August and October 1915, was promoted to temporary captain on 1 September 1915 and having his first taste of staff work being appointed temporary Staff Captain in India from 23 to 30 September 1915.

He was then appointed a temporary major on the staff of the General Officer Commanding (GOC) the Cavalry Division, Mesopotamia Expeditionary Force from 26 September to 31 December 1918, then a GSO II[2] with G.H.Q., Mesopotamian Expeditionary Force 1 January to 8 June 1919.

[2] Promoted to Brevet Lieutenant Colonel on 1 July 1930, he attended the Imperial Defence College in 1933 and transferred to the 9th Royal Deccan Horse on 29 August 1933 as second in command and then was appointed lieutenant colonel and commanding officer (CO) of the regiment from 4 August 1934 to 2 June 1936.

[2][5] He was promoted to local Brigadier whilst officiating as Director Military Operations & Intelligence 18 March 1936 to 3 June 1936 and temporary Brigadier whilst appointed as Director Military Operations & Intelligence from 3 June 1936 to 17 September 1938,[2] and retained the temporary rank when appointed to command the 4th (Secunderabad) Cavalry Brigade on 17 September 1938.

Mayne was promoted to General Officer Commanding (GOC) of the 5th Indian Division in April 1941.

Under Mayne's command the major fighting was concluded by 5th Indian Division and took the Italian Commander-in-Chief's surrender.

He was friends with Indian army officers like Joyanto Nath Chaudhuri and actively promoted them to higher positions.