The CoD Zombies timeline is something that's very complicated for beginners, so here we have an (as far as we can) eazy timeline overview so you can understand it fully.

In the beginning, there was the Aether and the Keepers, beings from another world.The Keepers used the aether to create the Summoning Key , an item with reality-altering powers. However, they also found the Dark aether during their travels.This dark force would corrupt the Keepers touching it. These corrupted Keepers would later be known as, the Apothicons. Among these Keepers the Shadowman, a more powerful keeper that could switch to a human form. Using the dark aether, the corrupted keepers constructed the aether pyramid (MPD), which could harness the dark aether. Shortly after its creation, a war in Agartha (the "perfect world") broke out between the two factions. The Apothicons, knowing would to lose this war, sent the MPD to a moon in one of the newly discovered realms, known as Earth.

Having lost the war, the Apothicons were trapped and sealed within the dark aether that they hated. In time, they began to slowly change from their Keeper forms into weird and disguiting creatures. A new plan was made, a plan to escape the dark aether and take control of Agartha. By sending meteors of element 115 through portals into other realms, in the hope that the life forms would use the element to fight against themselves. In doing so, ruptures would be created in space, allowing the Apothicons to escape.

At some point, the Apothicons are finally released from their world and invade Earth. However, the Keepers and our hero's wielding mystical elemental staffs step forth to oppose them, so beginning The Great War. Together, the Keepers and hero's drive back the Apothicons, sending the Apothicans in the dark Aether once more.

In the year 1939, just before the 2nd world war.Dr. Ludvig Maxis formed Group 935 as an international German-led research team, and became its head scientist. Maxis wanted to use a mysterious new element, which he had named Element 115, to improve the human condition by developing advanced technologies, and made Dr. Edward Richtofen his senior assistant, much to his chagrin Richtofen wasn't an equal partner. However, the group's goal immediately stopped due to a lack of funding, and Maxis regretfully turned to making a contract with the Nazi Wunderwaffe Program to use 115 as a power source for deadly new weaponry to help the Nazies win the war. Maxis hoped that after the war, the generous funds and Germany's ultimate victory would put Group 935 in a much better position to help the world.

The plan fails and by doiung so unleaches chaos upon the world by setting zombies free. The Group 935 is Dismanteld and Dr. Richtofen is trapped in a crazy asylum called Verruckt, here he meets 3 other people; Takeo a japanese fighter, Nicolai an russian soldier and Dempsey who is an American plane fighter. Togehter they fight zombies and make an plan to free the world and reset it to its pre-zombie state.

They travel to diffrent places to find clues and find out that the have to go to the moon to shoot a huge amount of element 115 onto the MPD. First they have to search for something that can schoot such an amout of element 115, so Richtofen took them to the white house to get the missing weapon wich was made by Wunderwaffe.

once they shot the MPD with the Wunderwaffe DG3 there start appearing rifts all over the world with Apothicans appearing out out them which leads to the great war that was described in the beginning.