BIOGRAPHY
Abraham Lincoln Kieros was an American soldier who fought overseas. He was also a mutant, with the power to create explosions merely by clapping his hands. This didn’t save him from serious injury on the battlefield, though, leaving him virtually paralyzed. Back in the States, Kieros was condemned to the paraplegic ward of a Veteran’s Administrative Hospital in Atlanta. He was alive, technically, but little more – for over a decade he lay immobile in an iron lung, barely able to speak or turn his head, relying on machines to feed him and keep his body functional. One day, Abe was approached by Apocalypse, the Eternal One, a powerful mutant who sought heralds that would serve as vessels for his strength. By this point, Kieros would take any offer which allowed him to move and live again. Apocalypse took Abe with him, claiming a new Horseman of War. [X-Factor (1st series) #11]
As War, Kieros received neural-implants and an exo-skeletal armor which restored his mobility, letting him move, walk, even eat and feed himself for the first time in years. However, Apocalypse also used drugs and treatments to ensure the loyalty of his new servants. They were indoctrinated with his philosophy that the strongest survive, and the weak must earn their continued existence. These Horsemen were loyal but not mindless, for Apocalypse encouraged competition and initiative among his minions. War was initially combative with the emaciated girl Famine, while the elderly Pestilence used her deadly touch to keep the younger ones in line. They quarreled amongst each other aboard Apocalypse’s Celestial Ship while the Eternal One worked to engineer his final Horseman, the Angel of Death.
Still, Apocalypse desired unity among his followers, and so he sent the Horsemen out to test themselves against his old foes, X-Factor. The mutant heroes were an easy target at the time, as half the team was being pursued by news choppers through Manhattan. War and his two compatriots donned armored masks and flying mechanical horses to engage their targets. Like the soldier he once was, Abe tried giving orders to coordinate Famine and Pestilence, but they 
refused to listen and attacked independently. The Horsemen fought to out-do each other instead of using strategy, drawing out the battle long enough for the rest of X-Factor to arrive and help their teammates. Iceman created a massive glacier which froze the Horsemen, even preventing War from clapping his hands. Seeing them suitably humbled, Apocalypse teleported his Horsemen back to the Ship to confirm they had learned the lesson he wanted. [X-Factor (1st series) #19]
When Death was finally ready, Apocalypse allowed the Horsemen to choose their own leader through the trial of combat. War convinced Famine and Pestilence that they needed to take Death 
out first before turning on each other. His threat assessment was correct, but the Angel of Death quickly defeated the other Horsemen despite their numbers. His metal wings slashed open War’s exoskeleton with precision, leaving him immobile once more. [X-Factor (1st series) #23] Once the pecking order was established, however, War embraced Death as a brother to Apocalypse’s cause. Warren Worthington III had been an Angel, a hero, until his wings were brutalized and amputated. Only in Apocalypse’s service did he regain what he lost. Abraham Kieros felt a kinship with Warren over their shared losses, and he was grateful to have a partner who shared his experience being reborn, thanks to the Eternal One. [Wolverine (2nd series) #147]
Apocalypse brought X-Factor to his Ship to announce his intention of testing humanity to weed out 
the weak and determine the strong. War and the other Horsemen challenged X-Factor before flying out into Manhattan to begin their Darwinist culling. War’s armor protected him from Cyclops and Marvel Girl, for it had a telekinetic inhibitor field and ruby quartz plating mirrored to reflect optic blasts. Cyclops tried to reason with him, but War fully embraced Apocalypse’s dogma and would not be swayed. War was not beaten by force, but by Iceman’s melting ice short-circuiting his armor, inhibiting his movements for the rest of the fight. Warren Worthington inevitably reconnected with his old friends and avoided War’s attempts to execute the traitor. Apocalypse fled, bringing the Horsemen with him and leaving behind his Ship to X-Factor as the spoils of war. [Fall of the Mutants crossover]
Although X-Factor won, one of their members named Caliban accepted Apocalypse’s vision and left with the Horsemen. He was later augmented by Apocalypse as they were, becoming his Hellhound. Apocalypse and the Horsemen monitored X-Factor from a distance as his Ship continued to test them, as he planned. [X-Factor (1st series) #26-27] Still, with Death gone and Pestilence dead during the attack, Caliban feared his master needed a full roster of Horsemen. He thought to check the Morlock Tunnels and the Alley for potential recruits among his old people. 
War and Famine were dubious, and went along to test the Morlocks and ensure they were truly among the strong. The commotion they caused drew the New Mutants down into the tunnels to investigate. War foolishly used his powers in battle repeatedly, threatening to bring the entire Alley down on everyone’s heads. The New Mutants’ example of bravery helped the Morlocks rise up against their attackers, and soon Caliban and the Horsemen were driven from the Alley. [X-Men: Legends (1st series) #11]
War and the Horsemen remained loyal to Apocalypse, but he passed them by to employ a new group of minions called the Riders of the Storm and seemingly perished. [X-Factor (1st series) #65-68] With his old rival gone, Mister Sinister used this opportunity to pose as Apocalypse, recruiting the gullible Horsemen for his own ends. War, Famine and Caliban (as the new Death) attacked Salem Center in Westchester County to capture Cyclops and Jean Grey. War fought with 
Iceman and Colossus until their mission was complete, and the Horsemen teleported away with their prizes. Sinister abandoned his pawns once he had what he wanted, leaving the Horsemen alone to face the X-Men who pursued the villains to find their missing friends. [X-Cutioner’s Song crossover]
[Note: Technically, only Caliban and Famine were defeated in part 4 of the crossover, but War was seen on the ground unconscious with his teammates in part 5.]
Without his patron, War eventually could no longer maintain his exoskeleton, and Abraham Kieros lost his mobility once more. Paralyzed, unable to move or speak, the former soldier was kept alive by machines in a hospital in Manhattan. During the Gathering of the Twelve, when Apocalypse prepared new Horsemen to guide his ascension, Archangel was infused with immense levels of living light. He still remembered his conversations with War, how Kieros would have done anything 
to walk again. With his light-based energy wings and new powers, Warren sought out Abe’s hospital room. By expelling all the new energies at his disposal, Archangel healed Abraham from his old injuries, restoring his ability to walk, move and live without machines supporting him. Abraham Kieros was incredibly grateful and found that his hope had been restored by this amazing act of kindness by a one-time ally turned foe. [Wolverine (2nd series) #147]