United States Marine Corps 1st Marine Division

United States Marine Corps 1st Marine Division
Unit name	1st Marine Division
Caption	Insignia of the 1st Marine Division
Dates	1941–present
Country	United States
Branch	United States Marine Corps
Type	Infantry division
Role	Expeditionary force-in-readiness; amphibious assault; ground combat
Size	Division
Command structure	I Marine Expeditionary Force
Garrison	Camp Pendleton
Nickname	"The Old Breed"
Motto	"No Better Friend, No Worse Enemy"
Battles	World War II, Korean War, Vietnam War, Gulf War, Iraq War, War in Afghanistan (2001–2021)
Notable commanders	Lewis Burwell "Chesty" Puller, Oliver P. Smith, Ray L. Smith
Decorations	Presidential Unit Citation (United States), Navy Unit Commendation

United States Marine Corps 1st Marine Division is the oldest and largest active division in the United States Marine Corps, established in 1941. As a principal ground combat element of I Marine Expeditionary Force, the division has fought in major World War II, Korean War, and Vietnam War campaigns and supported operations in Operation Desert Storm, Operation Iraqi Freedom, and Operation Enduring Freedom. The division’s historical reputation for sustained combat operations links it to notable amphibious assaults, island campaigns, and urban warfare.

History

The division formed from elements assigned to the Fleet Marine Force and deployed to the Pacific during World War II; early campaigns included the Guadalcanal Campaign, the Battle of Cape Gloucester, and the Battle of Peleliu. Postwar restructuring placed the division in the Pacific Ocean Areas to deter regional threats during the early Cold War and positioned it for rapid response in the Korean War, where it executed the Battle of Chosin Reservoir and defensive operations along the 38th Parallel (Korea). During the Vietnam War, the division engaged in major operations such as Operation Starlite, the Tet Offensive, and the Battle of Hue. Following withdrawal from Southeast Asia, the division participated in multinational exercises with Republic of Korea Armed Forces and contributed brigades to Operation Desert Shield and Operation Desert Storm, later generating Marine Expeditionary Units for Operation Iraqi Freedom and counterinsurgency missions in Al Anbar Governorate. Elements also supported Operation Enduring Freedom in Helmand Province and stability operations across the Indo-Pacific.

Organization and Structure

The division is subordinate to I Marine Expeditionary Force and typically organizes around a headquarters element, three infantry regiments, an artillery regiment, and combat support and service support units. Organic regiments include the 1st Marine Regiment, 5th Marine Regiment, and 7th Marine Regiment for maneuver, with the 11th Marine Regiment providing field artillery. Supporting commands historically attached include the 1st Marine Aircraft Wing for aviation coordination and the 1st Combat Engineer Battalion for mobility and countermobility. The division’s command and control integrates with joint task forces and NATO or Combined Joint Task Force structures when assigned to coalition operations.

Combat Operations and Deployments

Combat operations span amphibious assaults in the Pacific such as Guadalcanal Campaign and Battle of Okinawa; cold-weather conventional warfare in Korea during the Battle of Chosin Reservoir; counterinsurgency and conventional operations during the Vietnam War including Operation Hastings; and mechanized and urban operations in Operation Desert Storm and Operation Iraqi Freedom, notably the Battle of Fallujah (2004). The division has conducted humanitarian assistance and disaster relief missions within the Indo-Pacific and supported maritime security cooperation with partners such as Japan Self-Defense Forces and Republic of Korea Navy. Recent deployments have emphasized distributed operations, littoral maneuver with Navy Expeditionary Strike Group elements, and integration with Marine Raider Regiment and Special Purpose MAGTF taskings for irregular warfare.

Notable Units and Subordinate Elements

Key subordinate units include the 1st Marine Regiment ("The First Marines"), 5th Marine Regiment ("The Fighting Fifth"), 7th Marine Regiment, and the 11th Marine Regiment (artillery). Support formations have included the 1st Combat Engineer Battalion, 1st Reconnaissance Battalion, 1st Light Armored Reconnaissance Battalion, and 1st Tank Battalion during periods when armor was assigned. Aviation and logistics integration have involved the 3rd Marine Aircraft Wing elements and 1st Marine Logistics Group detachments during expeditionary deployments. Specialized companies such as Scout Sniper Platoons and Chemical, Biological, Radiological, Nuclear (CBRN) units have augmented the division for specific mission sets.

Equipment and Insignia

The division fields infantry small arms including the M4 carbine and support weapons like the Mk 19 grenade launcher, with crew-served assets such as the M2 Browning and anti-armor systems like the Javelin (missile system). Vehicular platforms historically employed include the Light Armored Vehicle, AAVP7A1, and main battle tanks such as the M1 Abrams when tank battalions were assigned; artillery formations have used the M777 howitzer and formerly the M198 howitzer. The division’s shoulder sleeve insignia—a red numeral "1" within an American-style design—and unit patches link to heraldic devices displayed on colors and guidons; campaign streamers and unit citations such as the Presidential Unit Citation (United States) adorn the division colors.

Lineage, Honors, and Awards

Lineage traces to activation in 1941 with successive redesignations reflecting wartime organization and postwar reorganizations within the Fleet Marine Force Pacific. Honors include multiple Presidential Unit Citation (United States) awards for actions in World War II, Korean War, and Vietnam War, as well as Navy Unit Commendation awards for later operations. Campaign credits encompass Pacific island campaigns, Korean campaign streamers, Vietnam service, and Southwest Asia and OIF campaign credits. Individual decorations awarded to division personnel include the Medal of Honor, Navy Cross, and Silver Star for conspicuous gallantry.

Notable Commanders and Personnel

Prominent leaders associated with the division include Lewis Burwell "Chesty" Puller early in his career within 1st Brigade elements, Oliver P. Smith for leadership during the Battle of Chosin Reservoir, and commanders such as Ray L. Smith. Distinguished Marines who served in the division include Medal of Honor recipients and senior leaders who later commanded at service and joint levels, connecting the division to broader Marine Corps institutional history and operational doctrine.

Category:United States Marine Corps divisions Category:Military units and formations established in 1941