4th Marine Division

4th Marine Division
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Unit name	4th Marine Division
Native name	Fourth Marine Division
Caption	Marines from the division embark for amphibious operations in the Pacific, 1944
Country	United States
Branch	United States Marine Corps
Type	Infantry division
Role	Amphibious warfare
Size	Division
Command structure	Fleet Marine Force Pacific
Garrison	Camp Lejeune
Nickname	Magnificent Fourth
Motto	Semper Fidelis
Battles	Battle of Kwajalein, Battle of Saipan (1944), Battle of Tinian, Battle of Iwo Jima, Operation Desert Storm, Operation Iraqi Freedom
Notable commanders	Harry Schmidt, James T. Moore

4th Marine Division The 4th Marine Division is a division-sized formation of the United States Marine Corps organized for ground combat, amphibious operations, and expeditionary warfare. Activated for major combat in the World War II Pacific campaign, the division later served in Cold War deployments, Gulf War, and 21st-century contingencies in Iraq and Afghanistan. Its history connects to major Marine Corps institutions, Pacific theater operations, and postwar reserve and active-duty force structures.

History

Activated in 1943 during World War II, the division trained for island campaigns under the supervision of Marine Corps Recruit Depot San Diego and commanders assigned from Marine Corps Schools. Early organization and doctrine development drew on lessons from the Guadalcanal Campaign and operational planning by staff officers who had served with I Marine Expeditionary Force elements. The division participated in the central Pacific thrust planned by Admiral Chester W. Nimitz and coordinated with amphibious shipping of the United States Navy. Postwar demobilization reflected decisions by the United States Department of Defense and the reorganization of United States Armed Forces in the late 1940s. During the Cold War the division was maintained in varying readiness categories, integrating lessons from Korean War amphibious operations and doctrine produced at Marine Corps Development and Education Command. Reactivations and reserve alignments tracked broader force posture shifts after the Vietnam War and into the Post–Cold War era.

Organization and Structure

The division consists of multiple subordinate regiments and battalions, including infantry regiments, artillery, reconnaissance, engineer, and support elements aligned with Marine Air-Ground Task Force principles. Core ground combat elements historically included the 23rd, 24th, and 25th Marine Regiments and the division's artillery assigned as 4th Marine Division Artillery. Command and control functions coordinate with higher echelons such as United States Marine Corps Forces Command and operationally with naval task forces led by United States Pacific Fleet. The organization uses standardized tables of organization and equipment promulgated by Headquarters Marine Corps and integrates logistics from Marine Corps Logistics Command, aviation coordination with Marine Aircraft Wing units, and intelligence support from Marine Corps Intelligence Activity.

Combat Operations

In World War II the division conducted assault and occupation operations during the Marshall Islands campaign, seizing atolls in the Battle of Kwajalein before participating in the Marianas campaign, including the costly Battle of Saipan (1944) and Battle of Tinian. Elements later reinforced the Battle of Iwo Jima, coordinating with United States Navy Seabees and Naval Construction Battalions for shore party operations. Postwar combat operations include attachments to coalition forces during Operation Desert Storm where Marine Expeditionary Units and division elements supported Coalition forces maneuver, and deployments during Operation Iraqi Freedom and counterinsurgency operations in Iraq and Afghanistan. Combat actions involved combined arms integration with M1 Abrams, Light Armored Vehicle, and artillery support from M777 howitzer and related fire support coordination with Forward Observers and naval gunfire liaison teams from United States Navy vessels.

Training and Deployment

Training cycles align with Marine Corps Training and Education Command standards and pre-deployment workups coordinated through Combat Logistics Regiment units and Marine Corps Installations such as Camp Pendleton and Camp Lejeune. Units conduct combined-arms live-fire exercises at ranges like Marine Corps Air Ground Combat Center Twentynine Palms and amphibious embarkation training aboard Amphibious Ready Group shipping with Navy amphibious assault ships including Wasp-class amphibious assault ship and America-class amphibious assault ship. Pre-deployment certification follows Unit Deployment Program or Marine Expeditionary Unit embark and integration with Navy Expeditionary Strike Group commanders and Joint Chiefs of Staff interoperability standards for multinational exercises with partners such as Japan Self-Defense Forces, Australian Defence Force, and Republic of Korea Armed Forces.

Unit Honors and Decorations

The division and its subordinate units have received campaign streamers and unit citations for actions in the Asiatic-Pacific Campaign and later operations. Decorations include campaign credits for World War II operations across the Marshall Islands, Marianas Islands campaign, and Iwo Jima, as well as unit commendations tied to Southwest Asia operations during Gulf War deployments and meritorious unit awards for actions during Operation Iraqi Freedom. Awards and honors are authorized by Secretary of the Navy approvals and displayed on unit colors in accordance with Marine Corps Orders.

Notable Commanders and Personnel

Notable leaders who commanded or served with the division include senior officers who later held flag appointments within the United States Marine Corps and joint commands, such as Harry Schmidt (USMC), James T. Moore (USMC), and other regimental commanders who contributed to doctrine at Marine Corps University. Enlisted and officer alumni have been recognized with individual awards including the Medal of Honor recipients attached to division operations during World War II, as well as recipients of the Navy Cross and Silver Star for later conflicts. Division veterans have participated in veteran organizations such as the American Legion and Veterans of Foreign Wars.

Category:United States Marine Corps divisions Category:Military units and formations established in 1943