A buffalo soldier was an African-American serving in one of the U.S. Army's African-American regiments. The term buffalo soldier is derived from an Indian term that described the perceived resemblance between the soldiers' hair and a buffalo's head hair. It is unclear whether the term originated in the Cheyenne, Apache, or Kiowa tribe. It is still a matter of contention whether the Indians meant respect or disrespect by using this term.
The regiments in which the buffalo soldiers served were the 9th and 10th Cavalry Regiments and the 38th, 39th, 40th, and 41st Infantry Regiments. These regiments were created by a reorganization act in 1866, and were meant to recognize African-Americans' contribution in the Civil War.
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HArd to explain.....
But it is like a society hiring one section of an exploited / enslaved population to fight against another section of another exploited / enslaved population in the same country.....
Example? The US Army hiring Blacks in the pre-civil war 1800s to kill Native American tribes.....The black soldier would be called a "Buffalo soldier."