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.Rottman, p. 42

US forces declared Saipan secure on 9 July 1944.

United States

Naval forces United States Pacific FleetRottman, p. 35 Admiral Chester W. Nimitz HQ at Pearl Harbor

United States Fifth Fleet 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

Ground forces

Expeditionary Troops (Task Force 56) Lieutenant General Holland M. 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

Left beaches

2nd Marine Division (21,746 officers and enlisted) Major General Thomas E. Watson Asst. Div. Cmdr.: Brig. Gen. Merritt A. Edson Red beaches 6th Marine Regiment 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 8th Marine Regiment 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 2nd Marine Regiment 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) 2nd Tank Battalion (USMC) Attached units 1st Battalion, 29th Marine Regiment (Lt. Col. Guy E. Tannyhill; Lt. Col. Rathvon M. Tompkins; Lt. Col. Jack P. Juhan)Johnston, Goldberg 715th Amphibian Tractor Battalion (Army)

Right beaches

4th Marine Division (21,618 officers and enlisted) Major General Harry Schmidt Asst. Div. Cmdr.: Brig. Gen. Samuel C. Cumming Blue beaches 23rd Marine Regiment 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 25th Marine Regiment 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 24th Marine Regiment 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) 4th Tank Battalion (USMC) Attached units 708th Amphibian Tank Battalion (Army) 773rd Amphibian Tractor Battalion (Army) 534th Amphibian Tractor Battalion (Army)

Expeditionary Troops reserve (Landed D+1)

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 165th 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 (Actual organic unit) 502nd Engineer Combat Battalion (No data to confirm existence) Navy UDT 5 UDT 6

Japan

Central Pacific Area Fleet HQRottman, p. 91 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 43rd Division 118th Infantry Regiment 135th Infantry Regiment 136th Infantry Regiment 47th Independent Mixed Brigade 315th Independent Infantry Battalion (Present at Tinian during the Battle) 316th Independent Infantry Battalion 317th Independent Infantry Battalion 9th Expeditionary Unit (a straggler unit; part was reorganized as 318th Independent Infantry Battalion) 1st Battalion, 18th Infantry Regiment Navy Units https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/j/japanese-naval-ground-forces.html 1st YOKOSUKA SNLF (1,326 personnel) 5th Base (1,049* personnel) 55th Guard Unit (2,504* personnel) 2 Construction Battalions Other units 3rd Independent Mountain Artillery Regiment 9th Tank Regiment (of 1st Tank Division) 3rd Battalion, 9th Independent Mixed Regiment 25th Antiaircraft Artillery Regiment 7th Independent Engineer Battalion 14th Independent Mortar Battalion 17th Independent Mortar Battalion Miscellaneous straggler units

See also Orders of battle involving United States Marine forces in the Pacific Theatre of World War II:

Battle of Guadalcanal order of battle Battle of Tarawa order of battle Guam (1944) order of battle Battle of Leyte opposing forces Battle of Peleliu opposing forces Battle of Iwo Jima order of battle Okinawa ground order of battle

Notes

References

Bibliography

External links Appendix A - Tactical Units of Northern Troops and Landing Force on Saipan Appendix C - Japanese Order of Battle on Saipan