Oct 23, 2010
Historian T. R. Fehrenbach (IIRC) says the "rebel yell" originated with the first Texas Rangers, the loose conglomeration of lawmen who defended early Texas pioneers from the Apache and Comanche warriors, combining still remembered ancestral Celtic war cries with Native American war whoops. Terry's Texas Rangers (CSA 8th Texas Cavalry, whose core consisted of men from the Rangers) introduced the cry to the Confederate Army.
It's a yell earlier Texas Rangers used to great effect against earlier Yankees. The Rangers were also known as giant-killers, who wore out many a filly.
Say it with me, with gusto: "YEEEEEEEHIIIIYAAAAAYYYYYHAAAAWWWWWWWWWW!!!"