In discussing the Korean War, T. R. Fehrenbach (in This Kind of War) references the subject of a couple of his other books, Comanches: The History of a People and Lone Star: A History of Texas and the Texans:
As many years earlier, when the cavalry fighting on the Plains had developed leaders such as Miles, Crook, and Ranald Mackenzie, men who rode hard, made cold camps, threw away their sabers, and moved without bugle calls, putting aside all the things they had learned in the War Between the States — but who had driven the Indians without surcease, hammering them across the snows and mountains until their women sickened and their infants died and they lost their heart for war, so the Army developed men who learned to fight in Asia.
Soldiers learned to travel light, but with full canteen and bandoleer, and to climb the endless hills. They learned to hold fast when the enemy flowed at them, because it was the safest thing to do. They learned to displace in good order when they had to. They learned to listen and obey. They learned all the things Americans have always learned from Appomattox to Berlin.
Above all, they learned to kill.
On the frontier, there is rarely gallantry or glamour to wars, whether they are against red Indians or Red Chinese. There is only killing.
Men of a tank battalion set spikes on the forward sponsons of their tanks, and to these affixed Chinese skulls. This battalion had come back from Kuniri, and the display matched their mood. They were ordered to remove the skulls, but the mood remained.
You might want to read An Apache Campaign, by John G. Bourke, Scribners (1958). This is a real story about a mounted patrol into Indian Country in 1883 in pursuit of Chiricahua Apaches.