'For conspicuous gallantry and devotion to duty. During the local operation at Rossignol Wood on July 14th 1918, Sergeant Mackay was in command of the carrying parties from the Battalion Dump to the Front line. The shelling on communication trenches and all the forward area during this operation was particularly heavy and our casualties in consequences were considerable. In spite of this Sergeant Mackay never once failed to carry out his duties, and rations, ammunition, etc., were delivered to the troops holding the new positions promptly. This NCO's conduct was also most conspicuous in the operations about Haplincourt on September 2nd 1918, handling his men with great skill and initiative contributing largely to the success of the operations. He showed a splendid example of courage, initiative, and devotion to duty which was an inspiration to all the men under his command.'
Source: London Gazette
Date: 13 March 1919