Stephen,
"Custer's" likely will never be remembered for that,his real fame is yet to come for his Indian-relationships.
Have you ever studied the Creek War of 1813-14 ? As Custer thought of himself as a Gen.Andrew Jackson famous Indian fighter(later U.S. President)who as "David Crockett" said- "We shot them like Dog's "(the Indian Dance to bullet proof themself's did not work)in Nov.1813-by 1814 Jackson forced the Creek Indians to forfeit 20 Million Ac for retribution of this War-Along with Sam Houston all became famous -some as -Indian fighter's from this war.

It all looks to have started from a family feud-Fulls viz-Halfs breeds?
His Civil War record is never really - had much to do with with his true fame. Hollywood never forgot him-100+ yrs later.

Jackson also forced all the Indians to Ok as President by the 1830"s-the being of the end for all the tribes.All of the Fort's were for protection from Indians-& bad men's.
The Railroads by the Mid- 1870's left the need for Fort's as a by gone Era of that time,as many of the old trails time had ended,and the Indian remained at peace-as now troops could be send by rail in short order.
This is how it looked to me anyway.