In response to the German battle cruiser raids on the British coast, a visible response was called for to quell public anxiety. On 27 May 1916, "Roberts" arrived at Gorleston to act as a guard ship for the port of Yarmouth, in effect acting as a coastal defence battery. "Roberts" fulfilled such duties at Tyneside and in the Thames Estuary for the rest of the war. Once again, Dewar was rotated back to shore, and was appointed to the Operations Division of the Naval Staff under first the Jellicoe, and then the Wemyss Boards of Admiralty. Dewar was promoted to the rank of captain on 30 June 1918 in the Half-Yearly lists and then became Assistant Director of Plans in the Plans Division. On 17 October 1919, he was appointed Commander of the Order of the British Empire (CBE) "for valuable services at the Peace Conference, Paris."