'Operations Messines: 7th June 1917 and operations opposite Warneton 17th June 1917. For conspicuous gallantry and devotion to duty. This Officer established a Battalion forward Headquarters between the second and third lines of German trenches west of Messines immediately after they were captured, and maintained his position under heavy and continuous shell fire until the Battalion was withdrawn thereby keeping open communication between companies in the attack and Battalion and Brigade Headquarters. On the morning of the 17th June Lieutenant Dean was sent to ascertain the true position of our posts after the capture of the Au Chasseur Cabaret. He traversed the complete front of the Battalion sector after daylight and under heavy shell and machine-gun fire, and fixed the exact location of all posts and thus cleared up a very obscure situation. His conduct throughout the campaign has been conspicuously good and a fine example to all under him.'
Source: London Gazette
Date: 1 January 1918