The 21st Field Artillery was constituted in the Regular Army on 1 July 1916 and organized at Camp Wilson, Texas on 1 June 1917.

The 21st Field Artillery fought in the World War II campaigns of Normandy, Northern France, the Rhineland, Ardennes-Alsace, and Central Europe.

Then activated 3 June 1948 at Fort Jackson, South Carolina, inactivated 30 April 1950 at Fort Jackson, South Carolina, activated 1 March 1951 at Indiantown Gap Military Reservation, Pennsylvania, inactivated 1 September 1953 at Indiantown Gap Military Reservation, Pennsylvania, activated 25 May 1954 in Germany, inactivated 1 June 1957 at Fort Ord, California, and relieved from assignment to the 5th Infantry Division; concurrently, redesignated as Headquarters and Headquarters Battery, 1st Battalion, 21st Artillery.

Additionally, Alpha and Bravo Batteries were awarded the Presidential Unit Citation for action in Binh Thaun Province.

In August 1990, the 1st Cavalry Division was alerted for deployment to Southwest Asia as part of the joint forces participating in Operation Desert Shield.

1st Cavalry Division MLRS fires from Alpha Battery, 21st Field Artillery illuminated the night skies and crippled Iraqi targets deep within enemy territory.

In September 1998, Charlie Battery, 1st Battalion, 21st Field Artillery deployed to Bosnia-Herzegovina to provide 24-hour radar support to Task Force Eagle.

68th Chemical Company's Smoke Platoon, while attached to 3rd Infantry Division, crossed the border into Iraq and were among the first U.S. soldiers to enter Baghdad.

During that time the task force conducted daily patrols, ambushes, raids, convoy escorts, target acquisition, and counter-battery cannon fires.

Fernandez was awarded the Silver Star for his actions on the night of 5 May, when his unit were ambushed while on a patrol through the city's Saidiyah neighborhood.

Falling under the newly formed fires brigade model, in 2006 the battalion fielded and manned the 575th Forward Support Company and Charlie (MLRS) Battery, 1–21 FA.

Charlie Battery, 1–21 FA received a change of mission in July 2008, and conducted convoy security operations in support of international police advisors and provincial reconstruction teams in Basra and Al Kut, Iraq.

On 12 June 2014, the battalion cased its colors for the seventh time during an inactivation ceremony in front of the 41st Fires Brigade Headquarters.