Career
MacMullen joined the Indian Army and served on the North West Frontier in 1897 and then with the Tibet Expedition in 1903. He saw action in World War I as a General Staff Officer Grade 1 with the 2nd Mounted Division during the Gallipoli Campaign and then as Brigadier-General on the General Staff with XV Corps in France. MacMullen served in the Third Anglo-Afghan War and then became Commander of the Bareilly Brigade in November 1919.
He went on to be Deputy Quartermaster-General in India in 1924, General Officer Commanding Rawalpindi District and 2nd Indian Division in March 1927 and Adjutant-General, India in May 1930.
He then became General Officer Commanding-in-Chief Eastern Command in April 1832 before retiring in April 1836.
