After only a short period of training, Whitelaw departed Australia on the transport "Hororata" on 19 October 1914 along with the first contingent of Australians bound for Egypt, arriving there in December 1914. On 25 April 1915 the battalion took part in the Landing at Anzac Cove as part of the second wave. Whitelaw disembarked with the battalion's machine gun section, but his time ashore was cut short when as he was evacuated later that day with a bullet wound to his foot. He spent a number of months recuperating in Egypt and in the United Kingdom before being repatriated to Australia in November 1915 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).