World War II engulfed the United States before Markab steamed into Ensenada Honda, Puerto Rico, her first port of call.

The new wartime demands on the Navy caused this voyage to terminate at Mobile, Alabama on 8 January 1942 where she was converted to a destroyer tender.

[1] After shakedown Markab transited the Panama Canal on 27 October to join Destroyer Force, Pacific Fleet at Pearl Harbor.

Ships recently returned from the battle for the Solomon Islands made use of her facilities for three months prior to her departure on 6 February 1943 to service the North Pacific Force.

Having assisted in preparing and sustaining the ships fighting in the bloody conquests of the Marianas and Iwo Jima, she sailed for the Philippines on 16 February 1945.

[1] When the Cold War turned hot in Korea, the resultant expansion of the Navy brought the temporary reactivation of Markab.

Operating initially at Newport, Rhode Island and after April, 1955 at Fall River, Massachusetts, Markab also participated in the semiannual fleet exercises.

Homeported at Alameda Naval Air Station, the repair ship sailed to Pearl Harbor late in October, returning 22 December.