Ultimate War is the most common name for the galactic conflict that began in 333 PA on Terra Nova during the events of Warrior Born, when the nations of CONON finally broke their age-old peace treaty and declared a civil war among Humans that would have consequences all across the Refuge.

At the beginning of the war in 333 PA, Humanity was split into two major warring groups. The first was led by Xarkon and included Zygbar and Grimm's Army. The second was led by Victory, with Yavakaro as their close ally.