Frank Hassett was born on 11 April 1918 in Marrickville, Sydney. He ended his career 59 years later as Australia's most senior soldier, the Chief of Defence Force Staff.

Hassett left school at the age of 15 and found work in the Department of Tramways. He soon grew bored with clerical work and sought a place at the Royal Military College, gaining entry only after receiving special consideration from Colonel Lavarack, the Chairman of the College's Selection Board. Hassett began his course in March 1935 aged 16 and by his third year in 1937 proved himself an able athlete and boxer. In 1938 he was promoted to under officer (senior cadet in a company, equivalent to company sergeant major).

Upon graduation, Hassett was posted to the Darwin Mobile Force and given command of a rifle platoon. At the outbreak of the Second World War he was posted to the 2/3rd Battalion of the 6th Division as Adjutant and sailed with the division for the Middle East in 1940. His first experience of battle came at Bardia and he was wounded on the eve of an attack on Tobruk. Having recovered he was sent to the British Army Staff College at Haifa and then promoted to major. Shortly afterwards he was posted as Brigade Major to the 18th Brigade in Syria.

When Japan entered the war, Hassett planned and controlled the brigade's embarkation from Suez and return to Australia, learning on his arrival that he had been promoted to lieutenant colonel. At 23 he was the youngest army officer to attain that rank. Postings - usually training appointments - in New South Wales, Queensland and New Guinea followed. He ended the Second World War as a staff officer with the 3rd Division on Bougainville without having had an operational command.

Hassett returned to Australia at the end of the war and worked as an instructor at the Australian Staff College, marrying Hallie Roberts in 1946. In 1948 he was posted as General Staff Officer (GSO) 1 to the 2nd Division, remaining there until March 1951 when he took command of the 1st Battalion, Royal Australian Regiment (1RAR). Three months later he was sent to Korea to command 3RAR. Hassett led the battalion through the battle of Maryang San, often exposing himself to artillery, mortar and small arms fire, and was awarded the Distinguished Service Order. He was considered by his men to be an inspirational leader.

After returning from Korea, Hassett took up a senior post at the Royal Military College Duntroon. He commanded the 28th Commonwealth Infantry Brigade Group in Malaya between 1960 and 1963, became General Officer in Command of Australia's Northern Command in 1968, and in 1971 was promoted to Vice Chief of the General Staff. After two years in this position he was made Chief of the General Staff and in 1975 became Chief of the Defence Force Staff. Ill health forced his retirement in 1977. Hassett died in Canberra on 11 June 2008.