Changes

Eventually, the [[Emperor]] would unite Terra, and established [[Treaty of Olympus|a union]] with Mars, bringing the red planet Red Planet back into the fold.{{Fn|2}} During the [[Great Crusade]], the [[Titan Legion]]s of Mars marched alongside the newly created [[Space Marine]]s.{{Fn|2}} However, during the [[Horus Heresy]] Mars became a key battleground as the loyalist Mechanicus and [[Dark Mechanicus]] split. In the resulting [[Schism of Mars]], which devastated the planet, the Dark Mechanicum eventually emerged victorious.{{Fn|4}} After the traitors took over Mars, the [[Imperial Fists]] blockaded the world for several years as the Heresy waged, only to be "liberated" by Horus' traitor forces during the final stage of the [[Solar War]].{{Fn|12}} Mars was again claimed by the Imperium after [[Horus]] was defeated in the [[Battle of Terra]].{{Fn|5}}