On 15 June 1944, United States Marine forces landed on the southwest coast of the island of Saipan in the central Marianas chain; these were followed a day later by US Army forces. This invasion was part of Operation Forager, an effort to recapture the entire Marianas chain from the Empire of Japan.
The island had been a Japanese possession since it was captured by the Imperial Japanese Army during World War I. As military conflict with the United States became increasingly likely during the 1930s, Japan expended great effort in fortifying Saipan. In mid-1944, nearly 30,000 troops were based on the island, almost double the estimates of US intelligence.[1]
US forces declared Saipan secure on 9 July 1944.
United States Pacific Fleet[2]
Admiral Chester W. Nimitz HQ at Pearl Harbor
Admiral Raymond A. Spruance in heavy cruiser Indianapolis
Joint Expeditionary Force (Task Force 51)
Vice Admiral Richmond Kelly Turner in amphibious command ship Rocky Mount
Northern Attack Force (Task Force 52 – Saipan and Tinian)
Vice Admiral Turner
Southern Attack Force (Task Force 53 – Guam)
Vice Admiral Richard L. Conolly in amphibious command ship Appalachian
Expeditionary Troops (Task Force 56)
Lieutenant General Holland M. "Howlin' Mad" Smith
Chief of Staff: Brig. Gen. Graves B. Erskine
Personnel Officer (G-1): Lt. Col. Albert F. Metze
Intelligence Officer (G-2): Col. St. Julien R. Marshall
Operations Officer (G-3): Col. John C. McQueen
Logistics Officer (G-4): Col. Raymond E. Knapp
Plans Officer (G-5): Col. Joseph T. Smith
Northern Troops and Landing Force (Task Group 56.1 – Tinian and Saipan)
Consisting of V Amphibious Corps
Southern Troops and Landing Force (Task Group 56.2 – Guam)
Consisting of III Amphibious Corps
V Amphibious Corps
Lieutenant General Holland M. Smith
Chief of Staff: Brig. Gen. Graves B. Erskine
XXIV Corps Artillery (Brig. Gen. Arthur M. Harper)
1st Provisional Gun Group
225th Field Artillery Howitzer Group
2nd Marine Division (21,746 officers and enlisted)
Major General Thomas E. Watson
Asst. Div. Cmdr.: Brig. Gen. Merritt A. Edson
Red beaches
Commanding Officer: Col. James P. Riseley
Executive Officer: Lt. Col. Kenneth F. McLeod
1st Battalion (Lt. Col. William K. Jones)
2nd Battalion (Lt. Col. Raymond L. Murray)
3rd Battalion (Lt. Col. John W. Easley)
Green beaches
Commanding Officer: Col. Clarence R. Wallace
Executive Officer: Lt. Col. Jack P. Juhan
1st Battalion (Lt. Col. Lawrence C. Hays Jr.)
2nd Battalion (Lt. Col. Henry P. Crowe)
3rd Battalion (Lt. Col. John C. Miller Jr.)
Floating reserve
Commanding Officer: Col. Walter J. Stuart
Executive Officer: Lt. Col. John H. Griebel
1st Battalion (Lt. Col. Wood B. Kyle)
2nd Battalion (Lt. Col. Richard C. Nutting)
3rd Battalion (Lt. Col. Arnold F. Johnston)
Landed after D-Day
10th Marine Regiment (Artillery)
Commanding Officer: Col. Raphael Griffin
Executive Officer: Lt. Col. Ralph E. Forsyth
1st Battalion (Lt. Col. Presley M. Rixey)
2nd Battalion (Lt. Col. George R. E. Shell)
3rd Battalion (Maj. William L. Crouch)
4th Battalion (Lt. Col. Kenneth A. Jorgensen)
18th Marine Regiment (Engineer)
Commanding Officer: Lt. Col. Ewart S. Laue
1st Battalion, 18th Marines (Lt. Col. August L. Vogt)
2nd Battalion, 18th Marines (Lt. Col. Chester J. Salazar)
Attached units
1st Battalion, 29th Marine Regiment (Lt. Col. Guy E. Tannyhill; Lt. Col. Rathvon M. Tompkins; Lt. Col. Jack P. Juhan)[3]
715th Amphibian Tractor Battalion (Army)
4th Marine Division (21,618 officers and enlisted)
Major General Harry Schmidt
Asst. Div. Cmdr.: Brig. Gen. Samuel C. Cumming
Blue beaches
Colonel Louis R. Jones
Exec. Ofc.: Lt. Col. John R. Lanigan
1st Battalion (Lt. Col. Ralph Haas)
2nd Battalion (Lt. Col. Edward J. Dillon)
3rd Battalion (Maj. John J. Cosgrove)
Yellow beaches
Colonel Merton J. Batchelder
Exec. Ofc.: Lt. Col. Clarence J. O'Donnell
1st Battalion (Lt. Col. Hollis U. Mustain)
2nd Battalion (Lt. Col. Lewis C. Hudson)
3rd Battalion (Lt. Col. Justice M. Chambers)
Floating reserve
Colonel Franklin A. Hart
Exec. Ofc.: Lt. Col. Austin R. Brunelli
1st Battalion (Lt. Col. Robert N. Fricke)
2nd Battalion (Lt. Col. Richard Rothwell)
3rd Battalion (Lt. Col. Otto Lessing)
Landed after D-Day
14th Marine Regiment (Artillery)
Colonel Louis G. DeHaven
Exec. Ofc.: Lt. Col. Randall M. Victory
1st Battalion (Lt. Col. Harry J. Zimmer)
2nd Battalion (Lt. Col. George B. Wilson Jr.)
3rd Battalion (Maj. Robert E. MacFarlane)
4th Battalion (Lt. Col. Carl A. Youngdale)
20th Marine Regiment (Engineer)
Lt. Colonel Nelson K. Brown
Exec. Ofc.: Capt. William M. Anderson
1st Battalion (Maj. Richard G. Ruby)
2nd Battalion (Maj. John H. Partridge)
Attached units
708th Amphibian Tank Battalion (Army)
773rd Amphibian Tractor Battalion (Army)
534th Amphibian Tractor Battalion (Army)
27th Infantry Division (Army) (16,404 officers and enlisted)
Major General Ralph C. Smith (thru 24 Jun)
Major General Sanderford Jarman (24 Jun thru 28 Jun)
Major General George W. Griner (after 28 Jun)
Blue beaches
Infantry
105th Infantry Regiment
106th Infantry Regiment
Artillery
104th Field Artillery Battalion
105th Field Artillery Battalion
106th Field Artillery Battalion
249th Field Artillery Battalion
Armor
762nd Tank Battalion
766th Tank Battalion
Engineer
102nd Engineer Combat Battalion
502nd Engineer Combat Battalion
Navy
UDT 5
UDT 6
Central Pacific Area Fleet HQ[4]
Vice Admiral Chūichi Nagumo (self-inflicted gunshot 6 July)
Chief of staff: Rear Adm. Hideo Yano (seppuku 7 July)
Thirty-first Army
Lieutenant General Hideyoshi Obata (on inspection tour of Guam during battle; seppuku there 11 August)
14th Air Fleet
Defenses of Saipan
Lieutenant General Yoshitsugu Saito (seppuku 7 July)
Approx. 25,500 army and 6,200 navy personnel
118th Infantry Regiment
135th Infantry Regiment
136th Infantry Regiment
Divisional support
47th Independent Mixed Brigade
316th Independent Infantry Battalion
317th Independent Infantry Battalion
318th Independent Infantry Battalion
Other units
3rd Independent Mountain Artillery Regiment
9th Tank Regiment (of 1st Tank Division)
3rd Battalion, 9th Independent Mixed Regiment
1st Battalion, 18th Infantry Regiment
25th Antiaircraft Artillery Regiment
7th Independent Engineer Battalion
14th Independent Mortar Battalion
17th Independent Mortar Battalion
Miscellaneous straggler units
Orders of battle involving United States Marine forces in the Pacific Theatre of World War II: