 Symon entered the Royal Military College, Duntroon, as an Australian Army officer cadet in 1979, and was allotted to Kokoda Company.In his final year at Duntroon in 1982 he was the senior cadet – Battalion Sergeant Major – and graduated as the recipient of the Sword of Honour.Symon was allotted to the Royal Regiment of Australian Artillery (RAA) and over his career saw service with the gunners in many postings, culminating in command of the 1st Field Regiment, Royal Australian Artillery in 1998 to 1999.