The Universal Century began when humanity migrated to space, leading to conflicts between the new Earth Federation and other interstellar colonial factions. The most notable conflict was the "One Year War" in U.C. 0079, where Earth clashed with the Principality of Zeon. This war, depicted in the original Mobile Suit Gundam, introduced Mobile Suits and shifted the balance of warfare. It was a devastating event, resulting in significant casualties and altering the course of history.