1st Marine Division (United States)

1st Marine Division (United States)
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Unit name	1st Marine Division
Caption	1st Marine Division shoulder sleeve insignia
Dates	22 December 1940–present
Country	United States
Branch	United States Marine Corps
Type	Infantry division
Role	Amphibious assault, combined arms
Size	~20,000
Command structure	III Marine Expeditionary Force
Garrison	Camp Pendleton, California
Nickname	The Old Breed
Motto	No Better Friend, No Worse Enemy
Colors	Blue and Gold
Mascot	Horseshoe insignia
Battle honours	World War II, Korean War, Vietnam War, Gulf War, Iraq War, War in Afghanistan

1st Marine Division (United States) The 1st Marine Division is the oldest and largest active-duty division in the United States Marine Corps, with lineage tracing to pre-World War II expansions and campaigns. It is a principal maneuver element within III Marine Expeditionary Force and has fought in major twentieth- and twenty-first-century conflicts including World War II, the Korean War, the Vietnam War, the Gulf War, the Iraq War, and the War in Afghanistan (2001–2021). The division is renowned for its role in amphibious operations, combined arms doctrine, and producing decorated leaders recognized by awards such as the Medal of Honor and the Navy Cross.

History

Activated on 22 December 1940 at Quantico, Virginia, the division was formed during the Roosevelt administration as tensions rose in the Pacific between the Empire of Japan and the United States. During World War II, subordinate units such as the 5th Marine Regiment, 7th Marine Regiment, and 11th Marine Regiment participated in the Guadalcanal Campaign, Battle of Cape Gloucester, and the Battle of Peleliu, influencing campaigns planned by Admiral Chester W. Nimitz, General Douglas MacArthur, and Admiral William Halsey Jr.. After World War II the division returned to the United States and later fought in the Korean War, notably at the Battle of Inchon, the Chosin Reservoir, and the Battle of the Punchbowl, often coordinating with United Nations Command forces and elements of the U.S. Army and Republic of Korea Armed Forces.

In the Vietnam War the division's regiments operated from bases such as Chu Lai, Phu Bai, and Da Nang Air Base, engaging in operations like Operation Hastings and Operation Prairie. Post-Vietnam, the division underwent force restructuring during the Cold War, took part in Operation Desert Shield and Operation Desert Storm under CENTCOM, and later deployed to Somalia for Operation Restore Hope. After the 11 September 2001 attacks, divisional units deployed to Iraq for Operation Iraqi Freedom and to Afghanistan for Operation Enduring Freedom, working alongside units from the U.S. Navy, U.S. Air Force, and coalition partners such as the United Kingdom and Australia.

Organization and structure

The division typically comprises three infantry regiments—the 1st Marine Regiment, 5th Marine Regiment, and 7th Marine Regiment—an artillery regiment such as the 11th Marine Regiment, and armored, reconnaissance, engineer, and support battalions. Command elements include a Division Headquarters and the 1st Marine Division Band. During expeditionary operations the division forms a Marine Air-Ground Task Force integrating aviation units like Marine Aircraft Group 11 and logistics units including Combat Logistics Regiment 1. Historically the division has adapted structures influenced by doctrine from the Marine Corps Warfighting Publication series and coordination with United States European Command and United States Indo-Pacific Command during joint exercises like RIMPAC and Operation Cobra Gold.

Combat operations and deployments

In World War II the division's assault on Guadalcanal in 1942 marked the first major offensive by U.S. ground forces in the Pacific theater; later operations at Cape Gloucester and Peleliu were among the fiercest fought by regimental combat teams. The Korean War saw the division execute the amphibious Inchon landing and endure the frigid breakout at Chosin Reservoir against People's Volunteer Army forces. In Vietnam the division countered People's Army of Vietnam and Viet Cong operations, conducting search-and-destroy missions and pacification programs.

During Operation Desert Storm the division provided rapid maneuver elements during coalition advances into Iraq, and in Iraq War deployments it participated in urban operations in Fallujah and counterinsurgency in Al Anbar Governorate. In Afghanistan Marines from the division engaged in counterinsurgency, training of Afghan forces, and partnered operations with NATO elements. The division also supported humanitarian and disaster relief missions, collaborating with agencies like United States Agency for International Development during crises.

Unit insignia and traditions

The division shoulder sleeve insignia—an old-style blue and gold star with a fighting eagle motif—derives from early Marine Corps heraldry and was formalized during World War II. The nickname "The Old Breed" stems from the division's reputation established by leaders such as Lieutenant General Holland Smith and chronicled by veterans including Eugene Sledge and Robert Leckie. Traditions include unit ceremonies at Camp Pendleton, the preservation of campaign streamers for actions at Saipan, Iwo Jima, and Pusan Perimeter, and a strong association with Marine Corps values promulgated at institutions like the Marine Corps University and the National WWII Museum.

Notable personnel and honors

Prominent figures who served in the division include General Lewis "Chesty" Puller-adjacent officers, decorated Marines such as Major General Raymond G. Davis and Sergeant Major John L. Estrada, and authors like Eugene Sledge whose memoirs informed works by HBO and historians. Division members have received numerous decorations including multiple Medal of Honor awards, Navy Cross citations, and Presidential Unit Citations for actions at Guadalcanal, Chosin Reservoir, and Fallujah. The division's legacy is commemorated in museums such as the National Museum of the Marine Corps and memorials at Marine Corps Base Camp Pendleton.

Equipment and supporting units

The division fields infantry weapons like the M4 carbine, crew-served systems including the M240 machine gun, anti-armor platforms such as the Javelin (missile), and artillery including the M777 howitzer under the 11th Marine Regiment. Armored and mechanized support has included the M1 Abrams tank and Light Armored Vehicle platoons, while aviation support from units like Marine Aircraft Group 11 employs aircraft such as the AH-1Z Viper, MV-22 Osprey, and F/A-18 Hornet for close air support and assault support. Logistics and combat service support are provided by elements of Combat Logistics Regiment 1 and the 1st Maintenance Battalion, with medical services linked to Naval Medical Center San Diego and forward resuscitative capabilities.

Category:United States Marine Corps divisions Category:Military units and formations established in 1940