Just like Fort Pillow, the Poison Springs "Massacre" is over-stated, as far as the casualties incurred. The actions of the black Union troops after they were overrun (i.e., they would not lay down their arms) and the historical context is not taken into account as these black troops were fighting Texans and Choctaws from the Indian Territory who felt they were retaliating against atrocities committed against them and their families by these very same "1st Kansas Colored Infantry" soldiers.
Undoubtedly, atrocities did occur at Fort Pillow and Poison Springs, but generally there is no balance or context given for the cause of these events. At Poison Springs, retaliation was on the mind of many of the Confederate attackers (see Middle Boggy Depot, IT, Feb. 13, 1864). Also, little is said of the atrocities committed by the 2nd Kansas Colored Infantry after the battle of Jenkins Ferry, AR as they entered field hospitals and murdered wounded Confederate soldiers in their hospital beds. Of course, this action is "justified" or rationalized because of the so-called massacre of black Union troops a few days earlier at Poison Springs.
Just my two cents.
Jim