Mr Ashley enlisted in the Australian Army in 1979. During a career that spanned over 36 years, Mr Ashley held a range of positions including Company Sergeant Major of 6th Battalion, the Royal Australian Regiment (6RAR); Regimental Sergeant Major (RSM) to 8th /7th Battalion, Royal Victoria Regiment; RSM 3 Brigade; 1st Division; and Command Sergeant Major of Land Command and Forces Command. Mr Ashley undertook deployments to South East Asia, East Timor and Timor Leste and also to Afghanistan. In 2011 he was appointed as the RSM of the Australian Army (the most senior non-commissioned officer in the Army) and retired from the position in July 2015.
In November 2016, Mr Ashley was appointed as a Member of the Defence Honours and Awards Appeals Tribunal for a period of three years, having earlier served as an acting Member.