USS San Diego
Armored Cruiser · United States · Lost 1918 · Long Island & the New York Approaches
The only major U.S. warship lost in World War I, sunk by a German mine within sight of the Long Island shore in 1918.
The Vessel and Her Loss
Launched in 1907 as USS California and renamed San Diego in 1914, this armored cruiser escorted Allied convoys across the North Atlantic during World War I. On July 19, 1918, while steaming toward New York, she struck a mine laid by the German submarine U-156 and sank within about 25 minutes, eight miles off Fire Island. Six of her roughly 1,183 crew were lost. A 2017 Navy survey confirmed the mine as the cause, ending a century of debate over sabotage or torpedo attack.
Vessel
- 1907
- ACR-6
- Union Iron Works
- San Francisco, California
- Steel
- 502 ft
- 69.5 ft
- 13680
- Steam, triple expansion engines, twin screw
- United States Navy
Loss
- July 19, 1918
- Enemy action
- About 8 miles off Fire Island, Long Island, New York
- Atlantic Ocean
- Escort duty in the North Atlantic → New York, New York
- Not established
- 1183
- 6
- Captain Harley H. Christy
The Wreck Today
- 110 ft
- Capsized and resting upside down on the seabed.
- Inverted
- Not established
- Listed on the National Register of Historic Places
Position
- 40.47° N 73.05° W
- Approximate position
- Fire Island, New York
Address of the NRHP-listed wreck site is restricted; position given is generally reported in public accounts.
Evidence
Overall confidence: Well documented (92/100)
Naval History and Heritage Command
Build history, loss cause confirmed by survey, casualty figures.
National Register of Historic Places nomination (NPS)
Wreck site listing, general location, and protected status.
