 On 9 December, U.S. Army Major General Alexander Patch — commanding general of the Americal Division — succeeded Vandegrift as commander of Allied forces on Guadalcanal and Tulagi. That same day, the 5th Marine Regiment departed the island, followed by the rest of the 1st Marine Division by the end of the month. Patch was ordered to eliminate all Japanese forces remaining on Guadalcanal. Patch told his superior — Millard Harmon, who commanded all U.S. Army forces in the South Pacific — that he needed more troops to accomplish his mission. In response, Harmon ordered the 25th Infantry Division — which was in the process of relocating from Hawaii to the South Pacific area — to ship directly to Guadalcanal. The 25th's units would arrive at Guadalcanal in stages during the last two weeks of December and the first week of January 1943. In addition, the rest of the 2nd Marine Division's units — including the 6th Marine Regiment — were ordered to Guadalcanal during the same time period. By 7 January, American forces on Guadalcanal would total just over 50,000 men.
