After shakedown along the United States East Coast, Long sailed late in the year for the Mediterranean.

Based at Cavite, Luzon, she patrolled the South China Sea until July 1922 when she was ordered to the United States.

Operating out of San Diego during the next decade, Long cruised primarily in the Pacific off North and Central America for division exercises and screen and plane guard duty.

Long operated along the United States West Coast and in Hawaiian waters with Mine Squadron 2.

After colliding with Monaghan in heavy fog 27 July, she repaired at San Francisco, California, returning to Kodiak on 27 September for screen and antisubmarine patrols.

During the Arctic winter, she patrolled the approaches to Adak and guarded convoys as American forces sought to defeat Japanese garrisons in the western Aleutians.

Long began mine sweeps in Lingayen Gulf 6 January, evading and firing upon Japanese aircraft as she carried out her intricate mission.

Later that afternoon a second plane attacked Long and exploded at the same spot, destroying the bridge and breaking the ship's back.