Red Cloud's War, fought from 1866 to 1868, was a direct response to the U.S. violation of the 1851 Fort Laramie Treaty. The construction of forts along the Bozeman Trail, a route used by gold prospectors cutting through sacred Lakota hunting grounds, ignited the conflict. Red Cloud's strategic brilliance was showcased in the Fetterman Massacre, where his warriors lured an 80-man U.S. cavalry unit into a trap, annihilating them. This defeat, the worst for the U.S. Army on the Plains at that time,