The USS San Diego Sank Off The Coast Of Fire Island, New York, Becoming The Only Major United States Navy Warship Lost In Combat During World War I. Originally Commissioned As The USS California (Armored Cruiser No. 6) In 1907, The Vessel Was Renamed In 1914 To Free The State Name For A New Battleship. As A Pennsylvania-Class Armored Cruiser, San Diego Represented An Important Transition In Naval Engineering, Featuring Mixed Coal-And-Oil-Fired Boilers And Enhanced Armor Compared To Earlier Vessels.
San Diego Served Actively In The Pacific Before The Outbreak Of World War I, Operating Along The West Coast And Participating In Exercises In The Hawaiian Islands. Following The U.S. Entry Into The War In April 1917, The Ship Was Assigned To The Atlantic Fleet And Based In Portsmouth, New Hampshire. From There, It Escorted Convoys Carrying Troops And Supplies To Europe, Guarding Against German U-Boat Attacks In The North Atlantic.
On Its Final Mission, The Cruiser Was En Route From Portsmouth To New York To Join Another Convoy. At Approximately 11:05 A.M. On July 19, 1918, A Sudden Explosion Occurred On The Port Side, Beneath The Engineering Spaces. The Ship Lost Power Almost Immediately. Within 30 Minutes, San Diego Had Rolled Onto Its Side And Sank In 110 Feet Of Water. Of The Approximately 1,183 Men Aboard, Six Were Killed In The Blast Or During The Evacuation. The Crew’s Response Was Disciplined And Effective, Preventing Further Loss Of Life.
Initial Investigations Considered Multiple Possibilities For The Cause Of The Sinking, Including A Torpedo From A German U-Boat Or An Internal Explosion. However, The U.S. Navy Court Of Inquiry Determined That The Likely Cause Was A German Mine, Probably Laid By The U-156, A German Submarine Operating Off The U.S. East Coast At The Time. U-156 Had Been Known To Lay Mines Along Major Shipping Routes. The Location Of The Damage On San Diego, Combined With The Lack Of A Torpedo Wake Or Confirmed Submarine Sighting, Supported This Conclusion.
The Sinking Of The USS San Diego Had Strategic And Symbolic Importance. It Marked A Rare Instance Of Direct Naval Combat Impacting U.S. Shores During The War. While The U.S. Mainland Was Largely Removed From The Front Lines, The Event Underscored The Reach Of German Naval Operations. Furthermore, It Highlighted The Importance Of Convoy Protection And Mine-Sweeping Operations Along The Eastern Seaboard.
San Diego’s Loss Was Widely Reported In The Press And Sparked Renewed Public Concern About German Sabotage And Submarine Activity. Although The Material Loss Was Limited Compared To Naval Engagements In European Waters, The Incident Emphasized The Need For Increased Coastal Surveillance, Improved Naval Intelligence, And Faster Mine Detection Techniques. The U.S. Navy Accelerated Deployment Of Submarine Chasers And Expanded Anti-Submarine Patrols In Response.
In Later Decades, The USS San Diego Became An Object Of Historical And Archaeological Interest. The Wreck Was First Explored Extensively By Navy Divers In The 1920s And Was Added To The National Register Of Historic Places In 1998. It Remains One Of The Most Visited Wreck Dive Sites In The Northeastern United States. Studies Conducted By The Naval History And Heritage Command And Underwater Archaeologists Confirmed That The Explosion’s Damage Pattern Matched That Of A Sea Mine Detonation, Supporting The 1918 Court Of Inquiry’s Conclusion.
Despite Its Fate, The Service History Of The USS San Diego Reflected The U.S. Navy’s Growing Role In Global Affairs During The Early Twentieth Century. The Ship Participated In Training Exercises, Fleet Maneuvers, And Diplomatic Visits That Helped Establish American Naval Presence On Both Coasts. Its Loss, While Tragic, Demonstrated The Increasing Complexity Of Modern Naval Warfare And The Risks Faced Even In Domestic Waters During A Global Conflict.
The Wreck Of The USS San Diego Continues To Serve As A Somber Reminder Of The Human Cost Of War And The Ever-Present Threat Of Undersea Weapons. It Is Also A Symbol Of The Courage And Discipline Displayed By Sailors Who Carried Out Their Duties With Precision And Resolve. The Ship’s Legacy Is Preserved Not Only In Historical Records But Also Beneath The Waters Off Long Island, Where Steel And Salt Still Guard Its Final Chapter.
References / More Knowledge:
Naval History And Heritage Command. “USS San Diego (ACR-6).” U.S. Navy, https://www.history.navy.mil.
Stillwell, Paul. Cruisers And Battle Cruisers. Naval Institute Press, 1984.
Tuleja, Thaddeus. Climax At Midway. Random House, 1960.
United States Navy. Report Of The Naval Court Of Inquiry Into The Loss Of USS San Diego, 1918.
NOAA Office Of National Marine Sanctuaries. “USS San Diego Shipwreck Site.” National Oceanic And Atmospheric Administration, https://sanctuaries.noaa.gov.