In November 1920 she evacuated civilians from the Crimea during the last stages of the Russian Civil War, and, until August 1921, operated off Palestine, Turkey, and Egypt on maneuvers.

Acting as screen ship and plane guard, Humphreys helped perfect the tactics of aircraft carrier warfare which were to exert a strong influence on the coming war.

Humphreys conducted shakedown off San Diego and sailed 13 November to join the Neutrality Patrol in the Caribbean, designed to protect American shipping.

During May and June 1940 the ship took part in a sound school at Newport to improve her antisubmarine capability, and sailed 4 December from Norfolk, Virginia for San Diego, where she arrived 2 days before Christmas.

During the critical early months she operated as a coastal escort ship between San Pedro and Seattle, Washington but in May she sailed northward to Kodiak, Alaska, arriving 31 May 1942.

After amphibious training in Hawaiian waters, the ship sailed to Noumea 22 January 1943 and began ferrying troops and supplies from advance bases to Guadalcanal, Tulagi, and Florida Island.

During these critical months as the ship repeatedly steamed to the Solomon Islands in support of amphibious assaults, she often fought off bombing and strafing attacks by Japanese aircraft.

After putting their troops ashore early 4 September, the high-speed transports remained off the beach to protect landing craft from Japanese air attack.

Humphreys sailed with other amphibious units for southern New Britain, arriving 15 December; put ashore elements of the 112th Cavalry Regiment[citation needed] in rubber boats to seize harbor islands; then stood offshore to provide gunfire support before retiring to Buna that afternoon.

These attacks became more intense as Humphreys entered Lingayen Gulf 6 January; and next day as her UDT team swam ashore for vital reconnaissance work, the ship provided gunfire cover.

[1] The ship arrived at Ulithi 23 January 1945 and took on a new duty, screening logistics groups during at-sea replenishment and refueling of the wide-ranging carrier striking forces.

[1] As an important preliminary to the main landings on Okinawa, Humphreys took part in the assault of Keise Shima 31 March, screening LST's and performing escort duties until 3 April when she sailed for Ulithi.

This last and largest of Pacific landings was then well underway, and the ship escorted resupply convoys from Ulithi to bitterly contested Okinawa until returning to Pearl Harbor 4 June 1945.