On 31 August 1918, at Road Wood, south-west of Bouchavesnes, near Peronne, France, when two companies became held up by machine gun fire, Cartwright attacked the gun alone under intense fire. He shot three of the crew, and, having bombed the post, captured the gun and nine enemy soldiers. For his actions he was recommended for the Victoria Cross. On 30 September 1918 he was wounded and evacuated to England. Cartwright was conferred with his VC by King George V, and at the end of the war Cartwright was repatriated to Australia, arriving in March 1919 and as the AIF was demobilised, he was discharged on 16 May 1919. For his war service he received the following medals: the Victoria Cross, the British War Medal and the Victory Medal.