After shakedown out of Bermuda, "Knapp" departed Boston on 26 November for the Pacific Ocean, arriving Pearl Harbor on 21 December. She departed Pearl Harbor on 16 January, with the aircraft carriers of Admiral Marc Mitscher's Task Force 58, headed for the Marshall Islands invasion. At sea on this duty from 16 January to 12 February when she put into Majuro, "Knapp" also bombarded Kwajalein. She continued her screening as carriers launched raids on Truk from 16–17 February and on bases in the Mariana Islands from 21 February to 22 February, then sailed from Majuro to Espiritu Santo to screen carriers providing air cover for the seizure of Emirau Island from 20 March to 25 March and raiding the Palau Islands, Yap, and Woleai from 30 March to 1 April.