(DD-51: dp. 1,050; l. 305'3"; b. 31'1"; dr. 9'6"; s. 29; cpl. 101; a. 4 4"; 8 21" tt.; cl. O'Brien)

The second O'Brien (DD-51) was laid down 8 September 1913 by William Cramp and Sons, Philadelphia, Launched 20 July 1914; sponsored by Miss Marcia Bradbury Campbell, great-great granddaughter of Gideon O'Brien, and commissioned 22 May 1915, Lt. Comdr. C. E. Courtney in command.

After shakedown between Newport and Hampton Roads, she was assigned to the 5th Division, Torpedo Flotilla Atlantic Fleet in December 1915. From early 1916 through the spring of 1917 she operated with the Fleet along the east coast and in Cuban waters.

Returning from winter maneuvers off Cuba in March 1917 the ship was in the York River when the United States entered World War I, 6 April 1917. After fitting out at Brooklyn Navy Yard, she got underway from New York 15 May 1917, and joined convoy at Halifax, Nova Scotia, enroute to Ireland. Upon arrival at Queenstown (now Cobh) 24 May 1917, she 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 miles off Queenstown 16 June 1917, 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 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 has shown that the contact, German submarine U-16, 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 patrol.

After the Armistice, she transported mail and passengers between Brest, France, and Plymouth, England. She returned to New York 8 January 1919, and decommissioned in Philadelphia 9 June 1922. O'Brien was struck from the Navy List 8 March 1935. Scrapped at Philadelphia Navy Yard, her materials were sold 23 April 1935.