I don't know why the Army didn't go to the S&W Schofield (too fragile?, too scarce ammo supply?) during the Indian Wars. Would be a Helluva faster ejecting and reloading when on horseback. At revolver range, the lower-powered 45 Schofield wouldn't have made that much of a difference. Check out hickok45 at 10:16.
They actually did.
The name Schofield was the name of the Major George W. Schofield of the US Army who helped develop the Smith & Wesson gun and cartridge that was adopted by the US Army. The Army bought MORE .45 Schofields than they ever bought of the Colt .45s. . .
In fact the name .45 LONG Colt came about because of Army Quartermaster Sergeants wanting to specify the LONGER, more powerful .45 Colt cartridge at their officers choosing, instead of the shorter .45 S&W Schofield which would safely chamber and shoot in the Colt revolvers and was the standardized Army round. These sergeants would write down .45 LONG Colt on the orders even though there was no such round by name and it became the name in popular nomenclature.