[1] In the pre-war years, he was involved in constructing bases in the northern part of Australia, including Larrakeyah Barracks in Darwin.
[1] He was also posted to the 4th Division in Melbourne, undertook training overseas and served in regimental appointments in Brisbane, Adelaide and then later Keswick, in South Australia.
[2] During the Second World War, McNicoll saw active service in the Middle East and in Europe, including a period on exchange with the Supreme Headquarters Allied Expeditionary Force, helping to plan the D-Day landings.
[2][4] He undertook a number of different staff appointments including Chief Engineer of Eastern Command and Engineer-in-Chief, Army Headquarters.
[5] He later wrote three volumes of the Royal Australian Engineers corps history, covering the periods from colonial Australia to the Second World War.