When the Communists invaded the Republic of Korea, she joined amphibious forces in Yokosuka, Japan on 9 July. Quickly converted in Japan for wartime operation, "Oglethorpe" carried equipment for the 1st Cavalry Division to Po Hung Dong, Korea, where the troops landed on 18 July. Returning to San Diego in August, she embarked men and equipment of the 1st Marine Division. Arriving off Inchon, Korea on 15 September, for six days she supported the amphibious assault which briefly reversed the course of the war, sending Communist troops scurrying back to North Korea.