After shakedown out of San Diego, "Hailey" departed Seattle 13 December 1943 to join the Pacific Fleet at Pearl Harbor. She sortied from Pearl Harbor 19 January 1944 screening a unit of Admiral Richmond Kelly Turner's Southern Attack Force for the assault and occupation of the Marshall Islands. Arriving off the southern tip of Kwajalein Atoll, "Hailey" joined the Southern Transport Screen and later stood offshore and pounded the enemy with her 5 inch guns. She sailed from Kwajalein 15 February with the Eniwetok Expeditionary Group and arrived off Eniwetok next day to screen the heavy ships; then joined Admiral Jesse Oldendorf's Northern Support Group in battering strong enemy emplacements before retiring to Majuro Atoll screening Manila Hay.