He set out with his two boats, HM "Coastal Motor Boat 4" and another, on 17 June 1919. One had to turn back before completing its mission, but Agar continued into the bay. The battleships were not in the harbour though. "CMB4" penetrated a destroyer screen and was closing on a larger warship further inshore when "CMB4", whose hull had been damaged by gunfire, broke down. She had to be taken alongside a breakwater for repairs and for twenty minutes was in full view of the enemy. The attack was then resumed and a Russian cruiser, the 6,645 ton was sunk, after which Agar retired to the safety of the open bay under heavy fire. For this he was awarded the Victoria Cross and was promoted to lieutenant commander on 30 June 1919.