Battle of Guadalcanal order of battle
The Guadalcanal Campaign, called Operation "Watchtower", was the first major Allied offensive in the Pacific Theater of Operations in World War II. The campaign lasted from the initial American landings on 7 August 1942 until the final Japanese evacuation on 9 February 1943, a period of six months, far longer than was expected by Allied planners. The initial 7 August landings on Guadalcanal itself and Tulagi across Savo Sound (the site of a Japanese seaplane base) were carried out by US Marines under the command of Major General Alexander A. Vandegrift. In recognition of  his courage and extraordinary leadership during the six-month struggle, he was awarded the Congressional Medal of Honor the following year. Forces of the US Army began arriving to relieve the exhausted Marines on 13 October. On 8 December Vandegrift was replaced by Major General Alexander M. Patch, US Army, who was named commander of the XIV Army Corps on 2 January 1943. Patch declared the island secure on 9 February. The 1st Marine Division's struggle to take Guadalcanal from the Imperial Japanese Army achieved legendary status: the heat and mud, the malaria and dysentery, the giant tropical insects  and the fanatical, often suicidal, resistance of the Japanese combined to create an immense amount of sheer suffering. Today, the unit's insignia features the word "Guadalcanal" superimposed on a large red numeral 1. Three future commandants of the Marine Corps fought on "The Canal": Alexander A. Vandegrift, Clifton B. Cates and Lemuel C. Shepherd. In addition to the action on the ground, the United States Navy and Imperial Japanese Navy fought several vicious and costly surface engagements at night in the waters of Savo Sound. Two nights after the initial landings, the US Navy experienced the worst open-water  defeat in its history at the Battle of Savo Island. By the time the Japanese had given up on Guadalcanal, they had lost 2 battleships, 2 heavy cruisers and 7 destroyers; Allied losses included 5 heavy cruisers (one of which was Australian), 2 light cruisers and a destroyer. Each side had an admiral killed in combat. After the war, the area was renamed Ironbottom Sound in reference to the number of ships sunk there. United States. Theater command. The roles of Commander in Chief, Pacific Ocean Areas (CINCPOA) and Commander in Chief, U.S. Pacific Fleet (CINCPAC), were both exercised by  Admiral Chester W. Nimitz from his headquarters at Pearl Harbor, Hawaii. Since the Solomons lie in the Southern Pacific, the landings of 7 August 1942 on Guadalcanal were the responsibility of the South Pacific Fleet, led by Vice Admiral Robert L. Ghormley from his headquarters at Nouméa, New Caledonia. Adm. Ghormley's pessimism, inadequate staff work and unwillingness to visit the front led Adm. Nimitz to replace him with the much more aggressive and hands-on Vice Admiral William F. Halsey on 18 October 1942. Operational command. Operational command of the invasion was assigned to Vice Admiral Frank Jack Fletcher . He also had direct command of the covering force, designated Task Force 61, where he flew his flag aboard fleet carrier "Saratoga". The amphibious forces, Task Force 62, were led by Rear Admiral Richmond Kelly Turner aboard attack transport "McCawley". Bitter disputes between Vice Adm. Fletcher and Rear Adm. Turner arose during both the planning and execution of the invasion. At issue was how long Fletcher's aircraft carriers would stay in the vicinity of Guadalcanal to provide air cover for Turner's support vessels in Savo Sound. The matter came to a head on D+1 (8 August), after two  days of assaults by bombers from the Japanese base at Rabaul. These attacks convinced Fletcher that his crucial aircraft carriers could not be risked in the waters of the Solomons any longer and his task force departed the area that evening. Unsettled by the removal of air cover and rattled on the morning of D+2 by the discovery that his cruiser screen had been decimated at the Battle of Savo Island, Turner ordered his vulnerable, and still half-full, cargo ships back to Nouméa around sundown 9 August. The Marine Corps forces ashore were thus left without air cover or  the planned level of food and ammunition. This suboptimal outcome was at least partially attributable to the decision to vest both overall mission command and carrier task force command in the same individual (Vice Adm. Fletcher). Marine forces. The D-Day (7 August) landings on Guadalcanal were carried out by the 1st and 3rd Battalions/5th Marines at 0910 hours, followed by the 1st Marines at 0930. Landings on the Florida Islands across Savo Sound were carried out earlier that morning by the 2nd Battalion/5th Marines, the 1st Parachute Battalion, and the 1st Marine Raider Battalion. The 7th Marines and 1st  Battalion/11th Marines arrived 18 September. The division began withdrawal from the island 12 December. Major General Alexander A. Vandegrift Asst. Div. Cmdr.: Brigadier General William H. Rupertus Brigadier General Alphonse DeCarre The 2nd Marines reinforced by the 3rd Battalion/10th Marines were part of the initial 7 August landings. The reinforced 8th Marines landed on 2 November and the reinforced 6th Marines on 4 January 1943. Army forces. Americal Division Major General Alexander M. Patch Major General J. Lawton Collins Service Command, South Pacific Theater of Operations Brigadier General Raymond E. S. Williamson Japanese. Seventeenth Army. Lieutenant General Harukichi Hyakutake 2nd  Infantry ("Sendai") Division Lieutenant General Masao Maruyama 38th Infantry Division Lieutenant General Tadayoshi Sano 35th Brigade Major General Kiyotaki Kawaguchi