Uncovering New Clues About A 99-Year-Old Underwater War Grave

World War I, which the U.S. joined 100 years ago, is often thought of as a distant war, whose casualties were suffered in other lands, and whose roots in the struggles facing Europe are as far from American soil as can be.

But in the summer of 1918, that war came very close to the Long Island shore, when the U.S. Navy armored cruiser San Diego, on its way to escort a convoy across the Atlantic, was sunk just off the Fire Island shore, killing six crew members.

Historians, oceanographers and archeologists spent a week off the South Shore in mid-September studying the shipwreck of the San Diego, in preparation for a presentation next summer commemorating the 100th Anniversary of her sinking.

They’re hoping, through the use of new imaging technology, to help answer the century-old question of whether the ship was torpedoed or tripped a mine, and also to help raise awareness of the preservation of war graves at sea.

The project is being conducted by the Naval History and Heritage Command, with the help of research tools being used by the University of Delaware’s College of Earth, Ocean and Environment.

“Studying sunken military craft offers researchers a glimpse into the lives of the sailors who served in them, as well as the Navy and the nation they served,” said NHHC’s Underwater Archaeology Branch Head Robert Neyland, Ph.D. “We believe the modern remote sensing and interpretive tools at our disposal now will help our understanding of the site and maybe teach us something new about what caused San Diego to sink.”

On July 19, 1918, the San Diego was bound for New York from the Portsmouth Navy Shipyard in New Hampshire when the impact occurred about 8 nautical miles south of Fire Island. Most of the ship’s crew, 1,180 men strong, were able to abandon ship.

The explosion, on the port side near the engine room below the waterline, was initially believed to be caused by a German torpedo, and Captain Harley H. Christy immediately ordered all guns to open fire on anything resembling a periscope. When the cruiser began to list and seemed in danger of capsizing, he ordered his men to abandon ship. He was the last person to leave. The ship sunk just 28 minutes after the impact.

A Naval Court of Inquiry the following month found no evidence of U-boats or torpedoes in the area, but did find several mines, leading to the conclusion that the German mine-laying submarine U-156 had earlier laid mines there.

This September 11 through 13, a team comprised of Naval History and Heritage Command and University of Delaware researchers, employing ship-based sidescan bathometric sonar on board the University of Delaware’s 46-foot R/V Joanne Daiber, along with tethered and autonomous underwater robots performing sonar and visual data collection, collected data to create a three dimensional map of the site.

“We’ve been very successful and have accomplished all of our objectives,” said Dr. Alexis Catsambis of the Naval History and Heritage Command, after wrapping up work on Sept. 13. “We have a very successful acoustic data set.”

Dr. Catsambis said the visual data collection at the site was not ideal, with low visibility due to Atlantic turbulence while their work was done in a brief weather window between storms.

“We were very lucky we were able to thread the needle between three separate hurricanes,” he said.

The site does contain many challenges — the ship lies upside down on the sea floor, where it is a popular dive site, and the intricacies of its 503-foot-long mass have led to more accidental diver deaths than the number of sailors who died in the original sinking.

“It has proven to be a complicated site,” said Dr. Catsambis. “It capsized on the surface — it listed and water came in through the gun ports. The crew had done everything right. They had 17 lookouts and everything was dogged down. The fact that only six men were lost was a testament to their determination, training and capabilities.”

Those six men were Thomas E. Davis, Engineman 2nd Class; Frazier O. Thomas, Machinist’s Mate 2nd Class; Paul J. Harris, Seaman 2nd class; Andrew Munson, Machinist’s Mate 2nd class; Clyde C. Blaine, Fireman 1st class, all of whom served with the U.S. Navy, and James F. Rochet, Engineman 2nd Class of the U.S. Naval Reserve Force.

Two of the men were killed instantly by the initial explosion, a crewman who had been oiling the port propeller shaft was never seen again, one crew member was killed when one of the smokestacks broke loose as the ship capsized, one was killed when a life raft fell on his head, and the sixth was trapped inside the crow’s nest and drowned.

All six men are now presumed to be interred with their ship in the waters off Long Island.

“We’re hoping this investigation, a year off from 100th Anniversary, will tell their story as accurately as possible,” said Dr. Catsambis of the sailors who died in the sinking. “We hope we’ll be able to tell the source of the impact from the type of damage and our knowledge of the types of mines or torpedoes the Germans would have used at the time. We feel very confident we have as much data as we can possibly obtain, short of additional visual data.”

Dr. Arthur Trembandis of the University of Delaware, an oceanographer, had worked with Dr. Catsambis in the past on mapping sites in the Mediterranean and Black seas.

“We were hoping to find a project to work on together again, and this was one where we had a laser-like focus on the site, mapping at a density level unlike any other we’ve done in our group,” he said on Sept. 13. “We’ve spent this week drinking from a fire hose of new data, but my preliminary sense is we’re getting the coverage and data that we want.”

“It’s really important for us to get students involved. Our primary mission is to help educate and instruct,” he said. “We brought a midshipman from the U.S. Naval Academy, and our students are front and center leading the efforts acquiring and processing the data.”

He added that the collaborative project, which was headquartered for the week at Coast Guard Station Fire Island, helped his students learn about career opportunities for engineers and archeologists within the Naval History and Heritage Command.

Dr. Trembandis said his team will now spend the next three to four months in the lab preparing the data to present to the Navy in a form they can use.

“There is a broader question. This site is a war grave, with unexploded ordnance on it,” said Dr. Catsambis. “It’s a popular dive site, and it has been disturbed in the past. We want to highlight the importance of preserving these sites from being disturbed.”

“People are absolutely allowed to dive there. The diving community in many instances has supported us in managing these sites, but recovery of material, and disturbance of the site is prohibited,” he added.

The teams are planning to present their findings next July at local commemorations of the 100th Anniversary of the sinking, which are currently in the planning phases.