 He served a term as private secretary to the Governor of Burma, Sir Charles Alexander Innes KCSI CSIE for which he was appointed Commander of the Order of the Indian Empire (CIE) in the 1931 New Year's honours list.In December 1937 was made brevet lieutenant-colonel for "distinguished services rendered in the field in connection with the operations in Waziristan, during the period 25th November, 1936, to i6th January, 1937".During World War II, Rees fought in the East African Campaign, the North African Campaign, and the Burma Campaign.