I believe the term "rackensacker" is derived from two words. Wrack and sack. Webster defines the word wrack as, unsound, damaged, a ruin. He also defines the word sack as, take by force, the plundering of a captured town, to pillage after capture, to loot. The first record I can find of this term being used is in The War With Mexico, 1846. The Arkansas Volunteer Calvary Regt., was known as, Rackensackers, Mounted Gunmen, and Yell's Mounted Devils, refering to Col. Archibald Yell, the commander.