After completing his training, Harold joined the ships company of HMS Mary Rose on the 15th June 1916. On the afternoon of the 16th October 1917, HMS Mary Rose left Marsten with twelve merchantmen and two armed trawlers in convoy bound for Shetland, joined later by HMS Strongbow. At 0600 hours the following morning HMS Strongbow sighted two German cruisers, the Bremse and the Brummer in poor visibility and mistook them for British cruisers. The Brummer closed to within 3000 yards and opened up with devastating fire, knocking out Strongbow’s main steampipe and wireless. Many of the hands below were scalded to death, those on deck were struck down by well-directed fire. The German ships then turned their attention to the merchantmen and quickly sank four of them. The Mary Rose had heard the firing astern of her and closed in to fight against desperate odds. Her Captain, Lieutenant-Commander Fox, had no idea that the convoy was being attacked by anything other than a submarine. A few moments later he sighted the German cruisers and grasped the real position. Without a moments’ hesitation he approached the enemy at high speed, and the gunners opened fire at a distance which was estimated at between 6000 and 7000 yards. When at a distance of about 2000 yards from the enemy Lieutenant-Commander Fox put the helm hard over, and the German gunners got the range as the Mary Rose was on the turn. After that the end came quickly. She sank in a very short time taking with her most of her compliment of 88 Officers and ratings, including her Captain, who was last seen swimming in the water just before the Mary Rose went down. A few survivors with one Officer, Sub Lt. Freeman manage d to escape on a raft. Sub-Lieutenant Freeman and the men from the Mary Rose reached the Norwegian coast near Bergen, where the lighthouse keepers took them in and fed them and attended to their injuries.