The Republic of Zeon was founded by Zeon Zum Deikun, and comprises the colonies located at Side 3.
History
The colonies declared their independence from the Earth Federation in U.C. 0058, and for the next several years they engaged in diplomatic issues surrounding their secession from the Earth Federation. The Republic of Zeon encountered many problems as the Earth Federation applied economic pressure on them in an attempt to force them to return to the Earth Federation. In U.C. 0068, the Republic of Zeon changed in leadership when Zeon Zum Deikun died suddenly, and his trusted adviser Degwin Zabi took his place. The Republic of Zeon continued on with its diplomatic and economic struggle till it changed its name and broke away from the Earth Federation, becoming the Principality of Zeon. Degwin abolished the Republic in August 15, U.C. 0069, and publicly declared the transition from republic government to a monarchy. This event and the subsequent attack by the Principality of Zeon sparked the One Year War.
Following the One Year War, the Republic of Zeon was re-established with a pro-Earth Federation government in control. Though regarded as Federation puppet, the Republic had been granted a degree of autonomy. However, the Federation planned to dissolve the Republic by U.C. 0100. The third Neo Zeon movement, known as "the Sleeves", led by Full Frontal continued to fight for Spacenoid independence. When the Vist Foundation offered them Laplace's Box, an enigmatic object that had the power to topple the Federation government, Frontal intended to use it as a time saver to forestall the dissolution of the Republic so it could help in forming the Side Co-Prosperity Sphere, which would boycott the Earth, forcing mass space migration and causing the Federation government to collapse. However, following the events of the Third Neo Zeon War, the Republic of Zeon retired their independence in U.C. 0100 and was folded back into the Earth Federation.