USS O'Brien (DD-51) - World War I

World War I

Returning from winter maneuvers off Cuba in March 1917, the ship was in the York River when the United States declared war on Germany on 6 April, entering World War I. After fitting out at Brooklyn Navy Yard, she got underway from New York on 15 May with Cummings, Nicholson, Cushing, and Sampson, and joined convoy at Halifax, Nova Scotia, en route to Ireland. Upon arrival at Queenstown on 24 May, O'Brien was assigned to the 6th Destroyer Division which cooperated with the British forces. She patrolled off the Irish coast in company with other destroyers answering distress calls and meeting eastbound convoys to escort them through the war zone.

While escorting SS Elysia 12 nmi (14 mi; 22 km) off Queenstown on 16 June, lookouts on O'Brien sighted a periscope. Heading toward the submarine for an attack, a lookout in the foretop saw the submerged boat pass close along the starboard side. A depth charge was dropped but no immediate evidence of damage was found. Nearly three hours later, the British vessel HMS Jessamine reported a large patch of oil in approximately the same position. The next morning, Cushing also reported and confirmed Jessamine's report. The British Admiralty believed the submarine was probably seriously damaged. However, later investigation reveals that German submarine U-16, the submarine in question, continued to operate and completed her cruise.

In the summer of 1918, O'Brien was transferred to the French coast where she continued her antisubmarine patrols through the end of the war.