After completing a Fellowship Diploma in Civil Engineering at the Royal Melbourne Institute of Technology, General Sanderson had a series of regimental postings. These included second in command of 10 Field Squadron and Troop Commander and Construction Officer of 21 Construction Squadron on operational service in Sabah, Malaysia. He was promoted to Captain in 1965.
Following eighteen months as a Staff Officer in the Office of the Engineer in Chief, he was posted as the Exchange Instructor at the Royal School of Military Engineering, Chatterden UK from 1967-1969. He returned to Australia to command 23 Construction Squadron at Holsworthy prior to taking up command of 17 Construction Squadron in South Vietnam at the end of 1970.
General Sanderson was promoted to Lieutenant Colonel in 1975 after serving for a short period as a Staff Officer at the Headquarters of Field Force Command. His initial appointment as Staff Officer Grade 1 at the Directorate of Engineers was followed by two years (1976-1978) as the Exchange Instructor, at the British Army Staff College, Camberley.
He commanded the 1st Field Engineer Regiment from 1979-1980, and then attended the Joint Services Staff College in 1981. General Sanderson was appointed as the Military Assistant to the Chief of the General Staff in late 1981, serving in that capacity until being promoted to Colonel as Director of Army Plans in 1983.
From June 1985 to the middle of the following year he attended the US Army War College, returning to Australia in the rank of Brigadier. After a six month period as Chairman of the Army Reserve Review Committee, he assumed command of the 1st Brigade at Holsworthy.
General Sanderson served as Chief of Staff Land Command for a brief period in 1989 and was then promoted to Major General and appointed as Assistant Chief of Defence Policy. In this role he was tasked to develop and carry out major reforms to the Higher ADF Staff, which resulted in him becoming the first Assistant Chief of Defence Force Development at the end of 1989.
From October 1991, General Sanderson became engaged directly in the United Nations process to bring peace to Cambodia, first as adviser to the Secretary General of the United Nations, and then from March 1992, in the rank of Lieutenant General as the Commander of the 16,000 strong international military component of the United Nations Transitional Authority in Cambodia (UNTAC).
After the successful completion of the UN mission in October 1993, General Sanderson returned to Australia to be appointed as the first Commander Joint Forces Australia (now COMAST), and developed this role until becoming Chief of the General Staff in June 1995. General Sanderson’s appointment was changed to Chief of the Army in 1997.
Over time General Sanderson’s service to Australia has been recognised by the award of Member of the Order of Australia (1985), Officer of the Order (1991) and Companion of the Order (1994). General Sanderson has also been recognised by the United States of America for his service to the region and the alliance by the award of the Legion of Merit – Commander Class.