The One Year War is a fictional conflict that drives the events of the anime series Mobile Suit Gundam and numerous side-stories set within the Universal Century timeline. Many games based on the Gundam franchise are either set during the course of the war or make direct reference to it. The war is fought between the forces of the Earth Federation, encompassing Earth and Federation-allied space colonies, and the Principality of Zeon, comprised of numerous colonies under the control of the Zabi family.
The war is fought over the course of the year U.C. 0079 and ends with Zeon's defeat thanks in large part to Amuro Ray, pilot of the Gundam, and the crew of the White Base.