From October through December 1915, Ericsson operated out of New York and Newport, Rhode Island on drills, in training and on the Neutrality Patrol. With the Torpedo Flotilla of the Atlantic Fleet, she sailed 7 January 1916 for maneuvers in the Caribbean, using Key West and Guantánamo Bay as bases. She returned to Newport 23 May.
Ericsson’s neutrality patrols along the East Coast intensified. On 9 October 1916, she sighted a German submarine close by Nantucket Shoal Lightship, with a Dutch merchantman hove to. A few minutes later, a U-boat fired three shots across the bow of a British merchantman and ordered her to abandon ship. Ericsson took off this ship’s passengers and crew, while other destroyers rescued the Dutch ship’s people and those of three other ships ordered abandoned and then sunk by the U-boat that day.
For the first three months of 1917, Ericsson again joined in exercises in the Caribbean before returning to New York City and Newport to prepare for distant service. On 7 May, she sailed from Boston for Queenstown, Ireland to join the pioneer American destroyer group which had reached Queenstown early in May. She began patrol duty in the war zone on 12 May and almost at once came upon a surfaced U-boat shelling two sailing ships. She opened fire, forcing the submarine down and preventing further attack and then picked up 37 survivors of the sailing ships. She continued on patrol and escort duty and, on the night of 28 September, sighted a surfaced submarine at which she fired. Ericsson dropped depth charges but, before she could carry out her plan to ram the German boat, lost contact in the darkness.
Ericsson continued to sail out of Queenstown on patrol and escorting convoys, many times attacking submarines, standing by damaged ships and rescuing survivors. After June 1918, she was based at Brest, France, and during that summer, usually sailed about three miles ahead of convoys, towing aloft a kite balloon used for observation.
At the close of the war, Ericsson was overhauled at Liverpool, but returned to Brest in time to take part 13 December in the welcoming honors rendered for President W. Wilson, arriving in France in the transport George Washington. On 21 December, she was homeward bound, arriving at New York 8 January 1919.
In May 1919, Ericsson sailed to the Azores to observe and support the historic first aerial crossing of the Atlantic, made by Navy seaplanes. After exercises along the East Coast and in the Caribbean, she entered New York Navy Yard for repairs and there was placed in reserve, still in commission, on7 August. She was laid up in reduced commission at Philadelphia and Charleston in the years that followed, and put to sea only during the summer of 1921, when drills and exercises took her to Newport.
Ericsson was decommissioned at Philadelphia on 16 June 1922 and transferred to the Treasury Department to augment the Coast Guard on 7 June 1924. Returned to naval custody on 23 May 1932, she was scrapped and her salvaged material sold 22 August 1934 in accordance with the London treaty reducing naval armaments.