On the outbreak of the
First World War he returned to England and on 8 October 1914, he enlisted in
19th (Service) Battalion (2nd Public Schools),
Royal Fusiliers. He was commissioned in
The Queen's (Royal West Surrey Regiment) in January 1915. Robertson was attached to the
Royal Engineers from June 1916 to February 1917, then to the Heavy Branch,
Machine Gun Corps (the Heavy Branch became the
Tank Corps). On 7 June 1917, at the
Battle of Messines, his
Mark IV tank was hit by a shell, which killed a sergeant and wounded two other crew. Although his tank was badly damaged, he brought it back to base. He was 26 years old, and an acting
captain in the Royal West Surrey Regiment,
British Army, attached to
A Battalion, Tank Corps during the
Battle of Broodseinde when the following deed took place for which he was awarded a Victoria Cross. On 4 October 1917 at
Zonnebeke, Belgium, Robertson was involved in the attack by the
21st Division between
Polygon Wood and the Menin Road. The attack was supported by the four tanks of 12 Section, A Battalion, with Robertson as section commander. Robertson and his
batman, Cyril Sheldon Allen, had spent the previous three days and nights reconnoitring the ground and marking routes with tape, and, during the attack, he led his tanks into action on foot. Fire from German pillboxes caused heavy casualties as they advanced through the muddy conditions of what had been the stream of the Polygonbeek. With the support of one of the tanks the pillboxes were captured and the higher ground overlooking the Reutel valley was reached by the supporting British infantry. The citation reads: As he had not married, his VC was presented to his mother by Brigadier General C. Williams CB at the
Royal Barracks, Dublin, on 27 March 1918. He is "believed to be buried" at
Oxford Road Commonwealth War Graves Commission Cemetery, north-east of
Ypres, in Plot III, Row F, Grave 7. His headstone bears the Latin inscription
VIRTUTIS GLORIA MERCES; "glory is the reward of virtue". he was killed on 20 November 1917. ==Memorials==