Robert (Bob) O'Neill was born on 6 November 1939 in Melbourne, Victoria. He joined the Australian Army in 1955 and graduated from the Royal Military College, Duntroon in 1958.
In 1965, Bob completed a Doctorate of Philosophy at the University of Oxford. His thesis, ‘The Relationship between the German Army and the Nazi Party, 1933-9' formed the basis for a book, The German Army and the Nazi Party, 1933-1939, published in 1966.
Bob deployed to South Vietnam in 1966 as an intelligence officer of the 5th Battalion, Royal Australian Regiment (5RAR). Intelligence officers depended on information from Vietnamese villagers about the enemy.
While serving in the Vietnam War, Bob was Mentioned in Dispatches for his leadership and courage. He showed great personal courage seeking out and confirming information on the ground and by air reconnaissance during the war.
After the Vietnam War, Bob pursued a career as a historian. He worked as a senior lecturer in History at the Royal Military College, Duntroon until 1969. He then became a strategic analyst and historian of war where he served as the Head of the Strategic and Defence Studies Centre at the Australian National University (ANU) from 1971 to 1982.
Bob was appointed the Official Historian for 2 volumes of the Korean War series. These were published jointly by the Australian War Memorial and the Australian Government Publishing Service in 1981 and 1985. Both series describe Australia's involvement in the Korean War at the political and strategic levels. His work delves into the wartime experiences of all three services: the Royal Australian Navy (RAN), the Australian Army and the Royal Australian Air Force (RAAF).
Later, Bob's career involved chairing many committees and councils, including the Trustees of the Imperial War Museum in London. He published many texts as an author and editor and was honoured with 5 awards, most notably the Officer of the Order of Australia in 1988.