Gavin Long selected the authors of the series, and these appointments were approved by a government committee. Long required that the authors have "some or all of three positive qualifications: experience of the events, proved ability to write lucidly and engagingly, [and] training as a historian". It was also decided that authors would not be able to write on topics in which they had played a leading part during the war. Selecting and engaging authors took up much of Long's time, and some potential authors declined offers of appointment. A replacement author for Chester Wilmot's volume on the Siege of Tobruk and Battle of El Alamein also had to be found in 1954 after he was killed in a plane crash. Once selected by Long, authors were confirmed by a committee comprising the Prime Minister, two or three other ministers and the Leader of the Opposition. Long and the general editor of the medical series were salaried and the other authors signed contracts to complete their work within a specified time frame and were paid in instalments as parts of their work were delivered. Of the 13 principal authors, five were academics and five were journalists. The official historians were supported by salaried research assistants who were members of the Australian Public Service and the project was administered by the Department of the Interior. Long retired in 1963, and his assistant Bill Sweeting assumed the role of editor.