This is the only unit to see combat in every major conflict since WWI

There are hundreds (if not thousands) of numbered units throughout the military, many with storied histories and with extensive combat roles since the United States military began operating on the world stage in the early 20^th Century. The U.S. Army’s 3^rd Infantry Regiment can trace its lineage all the way back to the American Revolution. The 1^st Infantry Division can claim to be the longest continuously serving division in the U.S. military. Even the U.S. Navy has the famed USS Constitution, the oldest commissioned sailing ship in the fleet. However, no unit has been deployed to every major conflict of the last one hundred years except for one — the 5^th Marine Regiment.

The 5^th Marine Regiment’s story begins on June 8, 1917, when it was activated in Philadelphia as part of the United States’ buildup for World War I. The Regiment was assigned to the 4^th Marine Brigade, which became a part of the U.S. Army’s 2^nd Division. The 5^th would establish itself in Marine Corps lore for its actions at the Battle of Belleau Wood in the spring of 1918. They would also fight at places such as Aisne and St. Mihiel, as well as the Meuse-Argonne Offensive.

During the regiment’s service in France, it earned its nickname, “the Fighting Fifth,” and was awarded the French Fourragère for receiving three Croix de Guerre citations, a decoration members of the 5^th Marines still wear today. The unit also had five folks (3 USMC, 2 USN) receive the Medal of Honor.

The next major action for the Fighting Fifth was battling their way across the Pacific in World War II. The 5^th landed on Guadalcanal on August 7, 1942 and endured four months of grueling combat on there before being relieved with the rest of the division on December 9, 1942. For their efforts during Guadalcanal, the 5^th Marines and the entire 1^st Marine Division received their first Presidential Unit Citation.

After a rest and refit in Australia, the 5^th Marines returned to combat in the late stages of Operation Cartwheel in late December 1943. They landed at Cape Gloucester, New Britain and would fight there until February 1944 when they were relieved by the 40^th Infantry Division. The Marines had another period of rest and refit before encountering their greatest challenges of the war, at Peleliu and Okinawa.

The 5^th Marines entered combat on Peleliu on September 15, 1944. Unbeknownst to them, the Japanese changed their tactics from attempting to stop landings at the beach to fortifying the entire island and creating a defense in depth. The lack of this knowledge would cost the Marines dearly. After the seizure of the airfield, the rest of the division set about clearing the remainder of the island.

By late October, the 5^th Marines were the only regiment still combat effective and their commander, Col. Harold Harris, turned to siege tactics to remove the Japanese, telling his officers “be lavish with ordnance and stingy with men’s lives.” The Marines handed over operations of the island to the 81^st Infantry Division and moved on to prepare for the invasion of Okinawa.

The 5^th Marines final action of the World War II was at Okinawa, where they landed along with the rest of the 1^st Marine Division and 6^th Marine Division on April 1, 1945. They were able to quickly clear the northern part of the island but Japanese resistance to the south would require extraordinary effort to reduce. The fight on Okinawa made places like Sugar Loaf Hill and Shuri Castle famous.In all of World War II four Marines from the 5^th were awarded the Medal of Honor. Following the fall of Okinawa and the Japanese surrender,  the 5^th was sent to China for occupation duty.

War soon found the 5^th Marines again when they were deployed as part of the Provisional Marine Brigade to the Pusan Perimeter in South Korea to shore up defenses against the invading North Koreans. The Fighting Fifth then rejoined their World War II counterparts, the 1^st and 7^th Marines, in reforming the 1^st Marine Division to take part in the landings at Inchon and the liberation of Seoul.

That winter the 5^th Marines fought for their lives at the “Frozen Chosin” Reservoir. When the situation looked bleak and the Marines were falling back Gen. Oliver Smith told his command, “Retreat, Hell! We’re not retreating, we’re just advancing in a different direction!”

After their withdrawal from North Korea, the 5^th Marines remained in the war and would hold off the Chinese attempts to break the Main Line of Resistance until the armistice in July 1953. The heroic efforts of the 5^th Marines garnered ten more Medals of Honor and another Presidential Unit Citation. The regiment left Korea in 1955.

Peacetime would not last long for the 5^th as just over a decade after leaving Korea they were deployed as part of the troop buildup in Vietnam in May 1966. The 5^th Marines and the rest of the 1^st Marine Division would spend six years battling the North Vietnamese Army and Vietcong. Their fighting spirit would make their name known once again, this time at places like Huế during the Tet Offensive. During the Vietnam War, seven members of the regiment received the Medal of Honor before returning to Camp Pendleton in 1971.

The 5^th Marines returned to combat once again against the forces of Saddam Hussein in 1991 as part of Operation Desert Storm. 1^st Battalion served as part of Task Force Ripper, while the 2^nd and 3^rd Battalions joined later and participated in the Liberation of Kuwait. The 5^th Marines returned to the Middle East in 2003 as part of the Invasion of Iraq where they spearheaded the Marine Corps efforts. After defeating Iraqi forces, the 5^th Marines remained in Iraq until October 2003, conducting security and stability operations. They would return to Iraq two more times, each time completing a 13-month deployment. Beginning in 2009 separate battalions of the 5th Marines began deployments to Afghanistan until the deployment of Regimental Combat Team 5 in 2011. 2nd Battalion was the last to deploy serving with RCT 6 in 2012.

In the nearly 100 years since the 5^th Marine Regiment was first formed, 24 Marines from the regiment have received the Medal of Honor, second only to the 7^th Marines 36 recipients. The 5^th Marines have also been a part of the 1^st Marine Division when it received all nine of its Presidential Unit Citations, as well as earning two of its own during the Korean and Vietnam Wars. According to the Marine Corps website, the 5^th Marines are the most decorated regiment in the Corps.