His war service was, however, cut short by a bullet wound suffered during the landing on 25 April 1915 and he returned to Australia where, during the interwar years, he transferred to the artillery and undertook a number of staff and instructional postings.

He retired from the military in 1951 with a number of high honours, nevertheless he continued his links with the Army and in 1955 he accepted the ceremonial role of Colonel Commandant of the Royal Australian Artillery, a post he held until 1961.

[1] The outbreak of the First World War interrupted Whitelaw's studies at the college before he could complete the full four-year course[2] as the Army decided to graduate the first class early so that they could be sent over to the Middle East with the Australian Imperial Force that was being raised for overseas service.

[3] As a result, shortly after the declaration of war Whitelaw was commissioned as a lieutenant in the AIF and posted to the 7th Battalion,[1] a volunteer infantry unit being raised in Melbourne.

[1] He spent a number of months recuperating in Egypt and in the United Kingdom before being repatriated to Australia in November 1915[5] whereupon his service in the AIF ceased and he returned to the Permanent Force, assigned to an administrative and instructional role in the 3rd Military District (Victoria).

During this time he undertook a couple of overseas study tours in his official capacity, first to the Netherlands East Indies and then to Singapore to investigate the development of coastal artillery in Allied forces.

In 1941, while serving as the aide-de-camp to Alexander Hore-Ruthven, 1st Earl of Gowrie in his capacity of governor general, Whitelaw received a temporary promotion to brigadier[1] and the following year was invested as a Commander of the Order of the British Empire.

[8][9] In April 1942 he was promoted to the rank of major general and posted to Land Headquarters in Melbourne where he was placed in charge of all artillery matters in the Australian Army, a task that encompassed a multitude of responsibilities including dealing with issues of supply to forward artillery units serving in the South West Pacific Area and the development of new weapons such as the Ordnance QF 25-pounder Short, which was designed specifically for the harsh conditions that the Army faced in the jungles of New Guinea and elsewhere.

[11] In his retirement Whitelaw undertook volunteer work with Legacy, a charitable organisation that cares for the dependents of deceased servicemen and women, and also the Victorian Country Fire Authority.

[16] In 1951, Lieutenant Colonel Whitelaw was General Staff Officer Grade 1 in the British Commonwealth Occupation Force in Kure, Japan, returning to Australia with his wife and son in April 1952.