This is the order of battle for the Guadalcanal campaign, called Operation Watchtower, 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 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. These were followed by units of the Naval Construction Battalions, known as CB's or Seabees.

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 high command of the Imperial Japanese Army did not take initially the Allied effort on Guadalcanal seriously and committed units piecemeal throughout the fall of 1942. Over the course of the campaign, the Japanese subjected two entire infantry divisions to massive attrition on the island.

The 1st Marine Division's struggle to take Guadalcanal 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. Vandegrift was awarded the Medal of Honor the following year in recognition of his courage and extraordinary leadership during the Corps's four-month struggle.

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.Morison 1949, pp. 250-251 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.Morison 1948, p. 183

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.Stille, p. 40 The 7th Marines and 1st Battalion/11th Marines arrived 18 September. The division began withdrawal from the island 12 December.

1st Marine Division Major General Alexander A. Vandegrift (CMoH recipient) Asst. Div. Cmdr.: Brigadier General William H. Rupertus

Division staff Chief of staff: Col. William C. James (to 24 Sep); Col. Gerald C. Thomas Asst. CoS for Personnel (D-1): Col. Robert C. Kilmartin Jr. Asst. CoS for Intelligence (D-2): Lt. Col. Frank B. Goettge () (to 12 Aug); Lt. Col. Edmund J. Buckley Asst. CoS for Operations (D-3): Lt. Col. Gerald C. Thomas (to 24 Sep); Lt. Col. Merrill B. Twining Asst. CoS for Logistics (D-4): Lt. Col. Randolph M. Pate

1st Marine Regiment Colonel Clifton B. Cates Exec. ofc.: Lt. Col. Julian N. Frisbie (to 23 Sep); Lt. Col. Edwin A. Pollock 1st Battalion: Lt. Col. Leonard B. Cresswell 2nd Battalion: Lt. Col. Edwin A. Pollock (to 23 Sep); Lt. Col. William W. Stickney 3rd Battalion: Lt. Col. William N. McKelvy Jr.

5th Marine Regiment Colonel Leroy P. Hunt (to 21 Sep) ; Colonel Merritt A. Edson Exec. ofc.: Col. William J. Whaling (to 25 Sep); Lt. Col. Walker A. Reaves (to 12 Oct); Lt. Col. William S. Fellers 1st Battalion: Lt. Col. William E. Maxwell (to 30 Aug); Maj. Donald W. Fuller (to 13 Oct); Maj. William K. Enright CMoH recipient: Cpl. Anthony Casamento 2nd Battalion: Lt. Col. Harold E. Rosecrans (to 11 Sep); Capt. Joseph J. Dudkowski (1-17, 25-30 Sep); Lt. Col. Walker A. Reaves (18-24 Sep); Maj. David S. McDougal (1-8 Oct); Maj. William J. Piper (8-11 Oct); Maj. Lewis W. Walt 3rd Battalion: Lt. Col. Frederick C. Biebush (to 22 Sep); Maj. Robert O. Bowen

7th Marine Regiment Colonel James W. Webb (to 20 Sep); Colonel Amor L. Sims Exec. ofc.: Col. Amor L. Sims (to 20 Sep); Lt. Col. Julian N. Frisbie 1st Battalion: Lt. Col. Lewis B. "Chesty" Puller CMoH recipient: Sgt. John Basilone 2nd Battalion: Lt. Col. Herman H. "Hard-Headed" Hanneken CMoH recipient: Lt. Mitchell Paige 3rd Battalion: Lt. Col. Edwin J. Farrell (to 24 Sep); Lt. Col. William R. Williams

11th Marine Regiment (Artillery) Colonel Pedro del Valle Exec. ofc.: Lt. Col. John A. Bemis (to 17 Oct); Lt. Col. Robert B. Luckey (to 28 Nov); Lt. Col. Thomas B. Hughes 1st Battalion: Lt. Col. Joseph R. Knowlan (to 19 Oct); Lt. Col. Manley L. Curry (to 28 Nov); Lt. Col. Donovan D. Sult (to 2 Dec) 2nd Battalion: Lt. Col. Edward G. Hagen (to 14 Sep); Maj. Forest C. Thompson 3rd Battalion: Lt. Col. James J. Keating 4th Battalion: Lt. Col. Melvin E. Fuller (to 28 Oct; from 7 Dec); Maj. Carl G.F. Korn (28-31 Oct); Capt. Albert H. Potter (to 6 Dec) 5th Battalion: Lt. Col. E. Hayden Price (to 18 Oct); Maj. Noah P. Wood, Jr.

Other Marine units 3rd Defense Battalion (landed 7 Aug): Col. Robert H. Pepper Executive officer: Lt. Col. Harold C. Roberts Operations officer: Maj. Samuel G. Taxis 1st Parachute Battalion: Maj. Charles A. Miller (to 18 Sep); Capt. Harry Torgerson (19-26 Sep); Maj. Robert H. Williams (from 27 Sep) 1st Raider Battalion: Col. Merritt A. Edson (CMoH recipient) (to 21 Sep); Lt. Col. Samuel B. Griffith (22-27 Sep) CMoH recipient: Maj. Kenneth D. Bailey () 1st Amphibian Tractor Battalion: Lt. Col. Walter W. Barr 1st Aviation Engineer Battalion: Maj. Thomas F. Riley 1st Pioneer Battalion: Maj. James G. Frazer (to 25 Oct); Maj. Henry H. Crockett 1st Medical Battalion: Cmdr. Don S. Knowlton, USN 1st Special Weapons Battalion: Maj. Robert B. Luckey (to 6 Oct); Maj. Richard W. Wallace 1st Tank Battalion: Maj. Harvey S. Walseth

2nd Marine Division 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. Division staff Asst. to commanding general: Col. Leo D. Hermle Chief of staff: Col. George F. Stockes Asst. CoS for Personnel (D-1): Maj. Lawrence C. Hays Jr. Asst. CoS for Intelligence (D-2): Maj. Thomas J. Colley Asst. CoS for Operations (D-3): Lt. Col. John H. Coffman Asst. CoS for Logistics (D-4): Maj. George N. Carroll Division special troops: Col. Maurice G. Holmes

2nd Marine Regiment Colonel John M. Arthur Exec. ofc.: Lt. Col. William S. Fellers (to 9 Oct); Lt. Col. Cornelius P. Van Ness 1st Battalion: Lt. Col. Robert E. Hill (to 10 Nov); Maj. Wood B. Kyle 2nd Battalion: Maj. Orin K. Pressley 3rd Battalion: Maj. Robert G. Hunt

6th Marine Regiment Colonel Gilder D. Jackson Jr. Exec. ofc.: Lt. Col. Alfred A. Watters (to 15 Dec); Lt. Col. Lyman G. Miller 1st Battalion: Lt. Col. Russell Lloyd 2nd Battalion: Maj. Raymond L. Murray 3rd Battalion: Maj. William A. Kengla

8th Marine Regiment Colonel Richard H. Jeschke Exec. ofc.: Lt. Col. James P. Riseley 1st Battalion: Lt. Col. Miles S. Newton (from 15 Jan. to 15 Nov, 1942); Maj. Joseph B. McCaffery 2nd Battalion: Lt. Col. John H. Cook Jr. 3rd Battalion: Lt. Col. Augustus H. Fricke

10th Marine Regiment (Artillery) Colonel Thomas E. Bourke Exec. ofc.: Lt. Col. Ralph E. Forsyth 1st Battalion: Lt. Col. Presley M. Rixey 2nd Battalion: Maj. George R. E. Shell 3rd Battalion: Lt. Col. Manly L. Curry (to 18 Oct; from 28 Nov); Lt. Col. Donovan D. Sult (18 Oct-28 Nov) 4th Battalion: Lt. Col. Kenneth A. Jorgensen

Other Marine units 2nd Amphibian Tractor Battalion: Maj. Henry C. Drewes 9th Defense Battalion (landed December 1942) Commanding officer: Col. David R. Nimmer Executive officer: Lt. Col. William J. Scheyer Operations officer: Capt. William C. Givens 2nd Raider Battalion ("Carlson's Raiders"): Lt. Col. Evans F. Carlson 2nd Special Weapons Battalion: Lt. Col. Paul D. Sherman 2nd Tank Battalion: Maj. Alexander B. Swenceski 6th Naval Construction Battalion: Lt. Cmdr. Joseph L. Blundon, CECNaval Heritage and History Command webpage, p. 6/84, Seabee Museum, Port Hueneme, CA (Started landing on 27 August) 3rd Battalion 18th Marines (started landing on 12 December)18th Naval Construction Battalion, Naval Heritage and History Command webpage, p. 21/88, Seabee Museum, Port Hueneme, CA

Army forces

Americal Division

Major General Alexander M. Patch Arrived in echelons beginning 13 October: 132nd Infantry Regiment (Illinois National Guard) 164th Infantry Regiment (North Dakota National Guard) Landed 13 October: 182nd Infantry Regiment (Massachusetts National Guard) Landed 12 November: 147th Infantry Regiment (Separate) (Ohio National Guard) 97th Field Artillery Battalion 214th Coast Artillery (United States) 244th Coast Artillery Regiment 221st Field Artillery Battalion 245th Field Artillery Battalion 246th Field Artillery Battalion 247th Field Artillery Battalion 57th Engineer Combat Battalion