20th Infantry Regiment Battalions
Modern Era, United States, Infantry
This page collects the existing battalion illustrations and additional documented historical battalions of the 20th Infantry Regiment. The historical entries include inactive units and earlier designations; the regimental image identifies entries without a battalion-specific illustration.
1st Battalion, 20th Infantry Regiment
This entry now anchors the battalion page in the regiment's origin or defining early identity, giving the 1st Battalion slot a more specific historical frame than the first scaffold pass.
The 20th Infantry Regiment originated in the Civil War as the 2d Battalion of the 11th Infantry and became a separate regiment in the 1866 postwar reorganization of the Regular Army. It then passed through the familiar sequence of frontier service, western posts, and late nineteenth-century overseas campaigning that shaped many old line infantry regiments. Its special designation, "Sykes' Regulars," linked it to the professional Regular Army tradition from which it emerged.
2d Battalion, 20th Infantry Regiment
The 2d Battalion entry uses the regiment's middle or operational arc to give the page a clearer sense of how the parent unit developed over time.
Vietnam-era service came through battalion and separate company deployments rather than through the regiment as a whole. The 1st Battalion deployed in 1967 with the 11th Infantry Brigade, while Company E served as a long-range patrol and security element under higher commands that included I Field Force and the 4th Infantry Division. That battalion-level service included the regiment's darkest notoriety through the My Lai massacre, which involved Company C, 1st Battalion, 20th Infantry.
3d Battalion, 20th Infantry Regiment
The 3d Battalion entry now carries the regiment into its later or enduring modern identity, tightening the page around the way the lineage is remembered in the modern Army.
In the late Cold War and after, the regiment's battalions served in Panama, Korea, and the Stryker force. The 5th Battalion, 20th Infantry served with the 2nd Infantry Division in Korea and later became part of the Stryker structure at Joint Base Lewis-McChord, linked to the 2nd Infantry Division. The regiment's twentieth-century history therefore moved from the 2d Division interwar years to the 6th Division in World War II, then to brigade- and battalion-level service in Vietnam and Korea.
4th Battalion, 20th Infantry Regiment
The 4th Battalion served with the 193d Infantry Brigade at Fort Clayton, Panama.
Its service there extended from the 1960s into the 1980s. Regimental history (Wikipedia).
5th Battalion, 20th Infantry Regiment
The 5th Battalion served in Korea from 1986 before moving to Fort Lewis in 1995.
It became one of the Army's first Stryker infantry battalions during the transformation of the 3d Brigade, 2d Infantry Division. Regimental history (Wikipedia).
Research note: The added historical entries cite their sources individually. Regimental illustrations are labeled as such. An earlier battalion designation can continue through another battalion or a separate battery; these relationships are identified in the entries. The original three entries are retained; the additional entries do not treat regimental campaign credits as evidence that every battalion fought in those campaigns.
Division timeline, 1916–2026 · assignments, patches and deployments →