The 415th Infantry was constituted in the Organized Reserve on 24 June 1921, assigned to the 104th Division, and allotted to the Ninth Corps Area.

The primary ROTC "feeder" school for new lieutenants for the regiment was the University of Wyoming.

[1] It was ordered into active service on 15 September 1942, and saw service during World War II with campaign participation credit for the Northern France, Rhineland, and Central Europe campaigns.

Inactivated during post-World War II demobilization, the regiment was reactivated 12 June 1947 as part of the Organized Reserve and headquartered in Tacoma, Washington under the 104th Division.

This article incorporates public domain material from 415th Regiment Lineage and Honors.