Origins
War Jack was a prisoner in The Slab until Joker broke out and used his Joker Gas on the inmates and used them to cause chaos all over the world.
Creation
War Jack was created by Chuck Dixon for his mini-series Joker: Last Laugh.
Major Story Arc
Joker: Last Laugh
For more information see: Joker: Last Laugh
Jokerized War Jack, White Dragon and Kilg%re are attacking downtown Atlanta. War Jack is able to keep Five Company pinned down, so that Kilg%re can attack. This plan seems to be working until Militia and the Blackhawks arrive and take down the jokerized villains