The Apocalypse is a belief that the world as we know it is coming to an end. In the Book of Revelation of the Bible, the Apocalypse is referenced. When the Apocalypse takes place, the Four Horsemen of the Apocalypse appear (Pestilence, also known as Conquest: Rider of the White Horse; War: Rider of the Red Horse; Famine: Rider of the Black Horse; and Death: Rider of the Pale Horse).
Darksiders takes place after an unlawful breaking of six of the seven seals sparking the End-War and setting the battlefield for the Battle of Armageddon. This apocalyptic war was waged by the kingdoms of Heaven and Hell with the Third Kingdom. That of man being the battleground, to determine the eternal fate over the souls of man upon Judgement Day. Heaven and Hell waged war in a way unseen before, all across the war-torn battlefield of Earth. Angels and Demons clashed. Archangels personally fought in the epic battle, elite Demons flexed their power, destroying everything in their path. The only form of order that existed was the devastation unleashed onto both kingdoms by the Red Horseman, War. In the aftermath of the Battle of Armageddon, the Third Kingdom was wiped away from existence. However, 100 years later the stranded forces of Heaven continued to wage an endless war against Hell and all its forces. While War is the main character of Darksiders, the horsemen known as Famine and Pestilence (Conquest in the old scriptures) have been replaced by the characters Fury and Strife, although the other three Horsemen do not appear in the first Darksiders game until just before the credits.