[1] In 1917 during World War I the unit was mustered into federal service as the 157th Infantry Regiment, as part of the 40th Division.

The 1st and 2nd Battalions (MLRS), 157th Field Artillery Regiment were disbanded in 2006 during the U.S. Army's restructuring from divisional organizations to the modular Brigade Combat Team model.

The regiment was reorganized as the 177th Infantry on 28 February 1921, with headquarters organized on 26 October 1921 and federally recognized at Denver, Colorado, and assigned to the newly-constituted 45th Division.

On 16 November 1921, per the National Defense Act of 1920, the regiment reassumed its World War I designation of the 157th Infantry.

The regiment conducted annual summer training most years at Camp George West, near Colorado Springs, from 1921–39, and in at least two years (1932–33), the regiment also trained some 17 company-grade infantry officers of the 103rd Division at Camp George West.

The DUI is a gold color metal and enamel device 1+1⁄8 inches (2.9 cm) in height overall consisting of a shield blazoned: Per fess embattled Gules and Or in chief two wigwams of the second garnished of the first and in base a sea horse brandishing a sword in dexter paw of the last.

Attached below and to the sides of the shield a Blue scroll inscribed "EAGER FOR DUTY" in Gold letters.

The shield is scarlet and yellow which are the Spanish colors; the parting line embattled in recollection of fortifications.

Headquarters Battery, 2nd Battalion (Colorado Springs) additionally entitled to: Battery C, 2nd Battalion (Pueblo) additionally entitled to: The 2012 historical novel, The Liberator: One World War II Soldier’s 500-Day Odyssey, by Alex Kershaw, focuses on 157th Infantry Regiment officer Felix L. Sparks and the men he led, all members of the "Thunderbirds".