On the break of the day of July 18 , 1918 , in the closing month of World War I , theUSS San Diegoleft the Portsmouth Naval Shipyard , New Hampshire bound for New York . Suddenly , it was struck by an unusual blow . Within just 28 minute , the hull had flooded and the ship began its journey to the seabed , sealing its fate as the only major US battlewagon to sink during World War 1 .

surprisingly , out of 1,100 crew , only six souls were lost .

Until now , no one was actually trusted what get the explosion . It was first suspected to be a mine , then later a hero , however , there was n’t much in the way of evidence to back this up . Over the years , others have suggested it was a sabotage or even just an chance event in the ember bunker .

A 2 - year project by theUS Naval History and Heritage Commandhas employ the help of underwater robotics , high - resolving power 3 - D images , and reckoner modeling to fix the one C - older mystery . Based on the damage to the wreckage and the modeled flooding scenario they believe the explosion was , in fact , a get by a mine lay by a German U - boat .

This further backed up German records find after the war that reveal the German submarineU-156was voyage around New York at the fourth dimension , plating explosive on warships . Just days afterward , U-156 really went on to carry out of theonly attack on US soilduring the   First World War .

“ The format of the 3 - calciferol modeling data make depth psychology pronto like , ” researcher Dr Alexis Catsambis , of the Naval History and Heritage Command ’s Underwater Archeology Branch , announcedat the American Geophysical Union ’s Fall Meeting this hebdomad .

“ Before we protrude this , I was n’t familiar with the ability to do this underwater ; above the body of water , we do it all the time , but below piddle compile 3 - D information is a challenge , " he added . " I ’ve learned that the bold amount of expertness that ’s call for to interpret it is a credit to the procession of technology in seafloor mapping . ”

Now home to hundreds of fish and lobsters , the shipwreck can be found beneath 34 meters ( 110 invertebrate foot ) of body of water just off the seacoast of Fire Island in New York . Dr Catsambis added that the team hopes their subaquatic excavations will help raise awareness and uphold the shipwreck site , as well as inform the   public about this moment in US history .

“ The legacy of the incident is that six men lost their animation on July 18 , 1918 , " Catsambis sound out .

“ With this pro , ject we had an opportunity to set the story direct and by doing so , abide by their memory and also formalise the fact that the gentleman onboard did everything mighty in the lead up to the attack as well as in the reply . The fact that we lost six men out of upwards of 1,100 is a will to how well they responded to the attack . ”