3rd Battalion, 5th Marines

3rd Battalion, 5th Marines is an infantry battalion of the United States Marine Corps assigned to the 1st Marine Regiment and the 1st Marine Division, based at Marine Corps Base Camp Pendleton. Formed in 1917, the battalion has served in major World War I, World War II, Korean War, and Vietnam War campaigns, as well as Operation Iraqi Freedom and Operation Enduring Freedom. The unit has earned numerous unit awards and campaign streamers through engagements at places such as Belleau Wood, Peleliu, Iwo Jima, Chosin Reservoir, and Fallujah.

History

3rd Battalion, 5th Marines was activated during the United States entry into World War I and deployed to the Western Front participating in the Aisne-Marne Offensive, Battle of Belleau Wood, Battle of Soissons, and the Meuse-Argonne Offensive. Between wars, the battalion took part in expeditionary duties including operations in Guantánamo Bay and the Caribbean Intervention (United States) era. In World War II, elements fought in the Guadalcanal Campaign, Battle of Cape Gloucester, Battle of Peleliu, and Battle of Okinawa. During the Korean War, the battalion participated in the Inchon Landing, the Battle of Chosin Reservoir, and operations along the 38th Parallel. In the Vietnam War, the battalion conducted counterinsurgency and major operations in provinces such as Quảng Nam Province and fought at Khe Sanh environs. Post-Cold War, the battalion deployed to Operation Desert Storm, Humanitarian aid and disaster relief operations in the Philippines, and the Global War on Terrorism with repeated deployments to Iraq and Afghanistan including major actions in Ramadi, Fallujah, and Marjah.

Organization and Role

The battalion is organized into a Headquarters and Service Company and three rifle companies—traditionally designated as Companies I, K, and L—along with a Weapons Company. It falls under the command of the 1st Marine Regiment and ultimately the 1st Marine Division, with administrative ties to Marine Corps Installations West. The battalion’s role aligns with Marine Air-Ground Task Force doctrine, providing infantry maneuver, combined arms integration with M1 Abrams, LAV-25, and coordination with MV-22 Osprey and AH-1Z Viper aviation. Training and logistics interoperability involve coordination with I Marine Expeditionary Force, U.S. Naval Forces Central Command, and joint entities such as United States Army XVIII Airborne Corps and United States Special Operations Command on expeditionary operations.

Combat Deployments and Operations

3/5 conducted amphibious assaults and sustained ground combat in major 20th-century campaigns, integrating with units like 2nd Marine Division, 3rd Marine Division, 5th Marine Regiment sister elements, and U.S. Navy task forces. In World War II, the battalion operated in the Pacific Theater of Operations under commands such as Admiral Chester W. Nimitz’s area. During the Korean War, 3/5 fought alongside United Nations Command forces and coordinated with U.S. Army X Corps. In Vietnam War deployments, the battalion executed search-and-destroy missions during operations linked to Operation Starlite and Operation Hastings. In the 21st century, 3/5 was a key maneuver element in Operation Iraqi Freedom urban combat in Fallujah and stabilization missions in Anbar Province, and later counterinsurgency and training missions in Helmand Province and Kabul during Operation Enduring Freedom. The battalion has also participated in multinational exercises including Talisman Sabre, RIMPAC, Combined Joint Task Force Horn of Africa engagements, and NATO interoperability events with partners such as Royal Marines, Australian Army, and British Army units.

Notable Engagements and Honors

The battalion’s lineage includes distinguished actions at Battle of Belleau Wood, where Marines earned accolades that contributed to the French Croix de Guerre awards to the regiment, and at Iwo Jima where personnel were involved in iconic fighting documented in works like Flags of Our Fathers. In Chosin Reservoir, the battalion fought in the freezing withdrawal later chronicled alongside figures such as General Douglas MacArthur and Major General Oliver P. Smith. During Vietnam War operations the battalion received citations for actions tied to commanders such as General William Westmoreland’s theater directives. In the Global War on Terrorism, 3/5 received unit commendations for combat in Iraq and Afghanistan, including awards related to operations in Fallujah that involved coordination with Iraqi Security Forces and Multi-National Corps – Iraq. The battalion’s members have been decorated with individual awards including the Medal of Honor, the Navy Cross, the Silver Star, and the Bronze Star Medal in various conflicts.

Training and Equipment

Training for 3/5 encompasses marksmanship at ranges like Marine Corps Base Camp Pendleton, live-fire urban training at facilities such as Integrated Training Exercise locales, and combined-arms training at Marine Corps Air Ground Combat Center Twentynine Palms. The battalion uses small arms and crew-served weapons including the M16 rifle, M4 carbine, M27 Infantry Automatic Rifle, M249 SAW, M240 machine gun, and anti-armor systems like the Javelin (missile system) and BGM-71 TOW. Fire support coordination integrates with M777 howitzer batteries and close air support from platforms such as the F-35B Lightning II, AH-64 Apache, and AV-8B Harrier II in past operations. Pre-deployment preparations involve coordination with Marine Corps Recruit Depot San Diego, School of Infantry West, and professional military education at Marine Corps University and Command and Staff College.

Category:Infantry battalions of the United States Marine Corps