It was as a torpedo and mining officer that Augustus Agar was selected for this service. He participated in the famous raid on Zeebrugge led by Commodore Roger Keyes, CMBs being used to lay smoke screens outside the mole to cover the escape of the crews of the blockships. During the summer of 1918, he was stationed at Dover and at Dunkirk, where the CMBs attacked German patrol craft along the Belgian coast.