The United States Army begins its incursion into Native-American territory along the Bozeman Trail.

Colonel Henry Carrington and a large force began his march from Fort Laramie into the Big Horn Mountains with the goal of building a series of forts along the Bozeman Trail to the west.  The action, which included the construction of Fort Phil Kearney in present-day Johnson County, Wyoming, incited fierce Native American resistance under Lakota chief Red Cloud.  What became know as Red Cloud's War lasted into 1868, when the U.S. Army was forced to withdraw the incursion and abandon Fort Phil Kearney.  (By John Osborne)