The 21st Infantry Regiment was constituted in the Regular Army as the 2nd Battalion, 12th Infantry Regiment on 3 May 1861. The battalion was organized at Fort Hamilton, NY on 20 May 1862. In 1866 the 2nd Battalion, 12th Infantry was reorganized and redesignated as the 21st Infantry Regiment. Known as the "Gimlet" regiment, the 21st Infantry has steadfastly and gallantly lived by its motto of "Duty" while serving the United States in the Civil War, the Indian Wars, the21st Infantry War with Spain, the Philippine Insurrection, World War II, the Korean War, Vietnam, the Panama Expedition and the War on Terrorism. In recognition of its accomplishments the 21st Infantry Regiment has earned two Presidential Unit Citations, two Valorous Unit Awards, a US Army Meritorious Unit Commendation, a US Navy Unit Commendation and 56 campaign streamers.
On 1 November 1967 the 4th Battalion, 21st Infantry was again activated at Schofield Barracks to serve as the fourth maneuver battalion for the 11th Light Infantry Brigade already in Vietnam. The 4th Battalion arrived in Vietnam on 14 April 1968. Based at Duc Pho in Quang Ngai Province, the 4th Battalion operated primarily in that region during the three plus years it was in Vietnam. The Duc Pho area was known as a rice bowl and it was fiercely fought over, with the 4th Battalion conducting numerous operations that significantly contributed to preventing the 3rd North Vietnamese Division and local Viet Cong forces from seizing this vital area. The 4th Battalion also operated in Quang Tin Province west of Tam Ky and at Dong Ha. From 15 February 1969 to 28 June 1971 the 4th Battalion was assigned to the 23rd Infantry Division (Americal). It was west of Tam Ky in Quang Tin Province on 26th August 1968 that Staff Sergeant Nicky Bacon of Company B, 4th Battalion, 21st Infantry earned the Medal of Honor. When two platoon leaders became casualties, SSG Bacon assumed command and led successful assaults against an enemy bunker and a machine gun nest, personally killing four Viet Cong at close range. He then climbed on the exposed deck of a tank and gave fire support to the rescue of trapped wounded and the elimination of the last enemy resistance. The 4th Battalion, 21st Infantry departed Vietnam on 28 June 1971 having participated in eight Vietnam campaigns and earning two awards of the Republic of Vietnam Cross of Gallantry with Palm. The 4th Battalion was inactivated that same date at Fort Lewis WA.
They arrived in country on April 14th 1968, Bravo company was led by Captain David Treadwell and was based out of Duc Pho, when in on Stand downs from the Bloody Jungle Floors of Nam in the I Corp, they would stand down at LZ Baldy, or Bronco, Charlie Brown, and many more, Bravo company was hit hard but hit the NVA alot harder in the last of August of 68 in TAM KY.