After three months of patrol in the Solomons, "Johnston" sailed to the Marshall Islands to prepare for the invasion and capture of Guam in the Marianas. On 21 July, she teamed up with the Pearl Harbor "ghost"—the battleship —to bombard Guam. The destroyer had fired over 4,000 shells by 30 July. "Johnston" next helped protect escort carriers providing air support for the invasion and capture of Peleliu.