Ships
- USS San Francisco (CA-38) Captain, 2 May 1942 – 16 May 1942
- USS Barnett (AP-11) In command, 7 August 1942
Henry Ehrman Thornhill was born on 15 June 1896. He was a member of the United States Naval Academy class of 1918 and joined the fleet near the end of the First World War. He stayed in the Navy, served through the Second World War, and held the rank of captain in 1942.
Before 1922 he commanded the submarines O-13 and O-14, small boats from the wartime building program that were still in service. He was promoted to commander on 1 April 1938. On 1 January 1942, in the first month of American participation in the Second World War, he was advanced to temporary captain.
From 2 May to 16 May 1942 Thornhill was captain of the heavy cruiser San Francisco. She was a New Orleans-class ship armed with nine 8-inch guns. On 7 December 1941 she had been in the Pearl Harbor Navy Yard, and in the spring of 1942 she was at sea with the Pacific Fleet. His command of the cruiser ran through those two weeks in May.
Six months after he left her, San Francisco fought in the Naval Battle of Guadalcanal. In the early hours of 13 November 1942 Captain Cassin Young was killed on her bridge. Rear Admiral Daniel Judson Callaghan, who was directing the American ships from San Francisco, was killed in the same action. Herbert Emery Schonland saw the cruiser through heavy shell damage and was awarded the Medal of Honor. Rear Admiral Norman Scott, who had commanded the American cruisers from San Francisco at Cape Esperance in October, died that same night on the light cruiser Atlanta.
Thornhill was promoted to captain on 30 June 1942. On 7 August 1942 he was in command of the transport Barnett. That day the ship formed part of the force landing the 1st Marine Division at Guadalcanal and Tulagi, the opening of the long campaign in the Solomon Islands. Thornhill died on 14 August 1963 and was buried at Fort Rosecrans National Cemetery in San Diego, his rank recorded as rear admiral.