[3] The ship left its convoy under radio silence to go on a mission to Dhahran in Saudi Arabia when it was torpedoed 185 kilometres (115 mi) off the coast of Oman by the German submarine U-859 on 28 August 1944.

The SS John Barry was carrying a cargo of 3 million American-minted Saudi one-riyal silver coins as an American payment associated with ARAMCO.

The reason for this shipment (one of several during the war) was that Saudi Arabia did not use paper money at the time and this led to a war-time shortage of currency with which to pay workers building new oil refineries and other US facilities at newly founded Dhahran.

Retired U.S. Navy Captain Brian Shoemaker, former General Counsel of the Navy, Hugh O'Neill, attorney H. McGuire "Mac" Riley of Howrey & Simon in Washington, D.C., and Jay Fiondella, owner of "Chez Jay", a celebrity-renowned seafood dive in Santa Monica, California, successfully bid for the salvage rights from the U.S. Government.

In October 1994, a modified drilling ship (Drillship was the FlexLD, formerly Sedco 445 and later Peregrin VII and now Deepwater Navigator), carrying a 50-ton video-equipped grab designed by IFREMER, sailed to the location of the John Barry.