The landing of the 1st Marine Division on Guadalcanal began on 7 August 1942. Taking the Japanese completely by surprise, the landing force moved ashore almost completely undisturbed and managed to quickly secure the island’s airfield, which would later be named Henderson Field. However, during the night of 8-9 August, a Japanese naval force surprised and defeated the U.S. Navy, forcing the American naval force and transports to retreat before they could unload all of the 1st Marine Division’s supplies, heavy equipment, and men. However, using the heavy equipment the Japanese left behind, the Marines finished the airfield and established a defensive perimeter. The first month of fighting at Guadalcanal consisted of patrolling the jungle with intermittent large-scale assaults made by the Japanese, such as the Battle of Tenaru, where the Marines defeated a near-suicidal onslaught of Japanese infantry. Throughout late August and early September, the Japanese ferried reinforcements to the island and launched a major offensive against the Marines near Lunga Ridge, beginning on the night of 12 September. After being repulsed several times with heavy casualties, the Japanese forces withdrew two days later. Despite the setback at Lunga Ridge, the Japanese prepared another offensive to be launched in late October; however, the Marines in turn began launching assaults against Japanese positions in late September and early October in the Matanikau Valley. Beginning on 24 October, the reinforced Japanese forces launched another major offensive against Henderson Field; after several days of relentless fighting, the Japanese withdrew after incurring massive losses while American casualties were comparatively light. Following up their success, the Marine and Army units launched their offensive, pushing the Japanese back toward a position near Point Cruz by mid-November and exacting a heavy toll on the Japanese defenders. By late November, the Japanese high command decided to abandon Guadalcanal and withdraw their forces starting in January. In December, the 1st Marine Division was replaced by the 2nd Marine Division as well as men from the 23rd and 25th Divisions from the Army, who then launched their successful offensive against the Japanese. By mid-January, the Japanese began withdrawing their forces and completed their evacuation of Guadalcanal by 7 February. In total, the Americans suffered around 7,000 total casualties compared to the Japanese who incurred over 30,000 casualties.