From her arrival at Key West 5 December 1913 until 16 June 1914, Cassin sailed with the 6th Division in the Caribbean and Gulf of Mexico in fleet maneuvers and exercises.
On 19 May 1914, she sailed to the rescue of SS Atlantis, wrecked off Tampico Bar. Taking the stricken ship’s passengers on board, she landed them at Tampico, Mexico. After overhaul, Cassin operated along the East Coast from 21 October until 27 January 1915, when she returned to the Caribbean for winter maneuvers.
Operations along the East Coast on neutrality patrol and drills and surveillance patrol in the Caribbean were Cassin’s employment until April 1917, when she was immediately prepared for overseas deployment. She arrived at Queenstown, Ireland with Ericsson, Jacob Jones, Rowan, Tucker and Winslow on 17 May, and began operations which called for her to rendezvous with American troop convoys at sea and escort them to ports in England and France. On 15 October, she sighted the German submarine U-61 southeast of Queenstown, about 20 miles off Mine Head, Ireland, and pursued her. At 1330, Cassin was struck in her port side, aft, by a torpedo. One man, Gunner’s Mate First Class Osmond Ingram was killed. Nine others were wounded and Cassin, with her rudder blown off and stern extensively damaged, began to circle. This did not prevent her, however, from firing four rounds at the submarine when she spotted its conning tower at 1430. The submarine, thus discouraged from further attack, submerged and was not contacted again. Through the night, Cassin was guarded by an American and two British destroyers, and in the morning, HMS Snowdrop took Cassin in tow for Queenstown. After repairs there and at Newport, England, Cassin returned to escort duty on 2 July 1918.
Cassin’s war service received a well-deserved honor on 12 and 13 December 1918, when she was chosen as one of the escort for the George Washington, carrying President Woodrow Wilson into Brest, France, for his attendance at the Versailles Peace Conference. Cassin returned to Boston, 3 January 1919.
After winter maneuvers in the Caribbean, Cassin cleared New York City 1 May 1919 for the Azores, where she took station guarding the route of the Navy’s historic transatlantic NC-4 flight. She returned to Boston for repairs; then sailed on to Philadelphia, where she was placed in reserve 18 June 1919 for more extensive repairs. Reactivated at Charleston 14 February 1921, Cassin joined Destroyer Flotilla 5 for operations along the New England coast until 11 October 1921, when she returned to Charleston.
Returning to Philadelphia 29 March 1922, she was decommissioned there 7 June 1922. Transferred to the Treasury Department on 28 April 1924 for service as Coast Guard cutter CG-1, Cassin was returned to naval custody 30 June 1933 and sold 22 August 1934.