On July 28, 1866, Congress passed an act that enabled Negroes to serve in the regular peacetime army.  The US Army, in 1866, was a poor shadow of its Civil War self.  Nearly a quarter of a million Union soldiers had marched in review thru Washington May 23-24, 1865 to celebrate the end of the Civil War.  Then in 1866, by its new legislation, Congress authorized six new regiments of Negro troops, two of cavalry and four of infantry.  Thus, former slaves gained the opportunity to play a major role in the settlement of the American west.