In February 1915, at the beginning of the Dardanelles Campaign, Admiral John de Robeck asked the Admiralty for a good surveying officer and Douglas was sent out to join the flagship . Later he transferred to and . De Robeck's dispatches contain several mentions of Douglas' "work of inestimable value to the fleet". His expertise was in fact indispensable for successful landing operations. His zeal and ability were recognized by promotion to acting captain in October 1915, confirmed at the end of the year. After the evacuation of the Gallipoli peninsula in January 1916 Douglas returned to the Admiralty and served as Director of the Naval Meteorological Service. Then in 1918 Admiral Roger Keyes, commanding the Dover Patrol, who had been with de Robeck in the Dardanelles campaign, asked for Douglas to join his staff at Dover to prepare for the Zeebrugge Raid and the First Ostend Raid in April 1918. After the raids Douglas was appointed CMG "in recognition of distinguished services during the operations against Zeebrugge and Ostend on the night of the 22nd–23rd April, 1918." He was also awarded the Belgian Order of Leopold and the Italian Medal of Military Valor.