Division of Altenburg

The Division of Altenburg (German: Altenburger Teilung) was the division of the Meissen lands of Altenburg between the two brothers Frederick II, Elector of Saxony and Duke Wilhelm III in 1445. The division caused hostilities between Frederick and Wilhelm. The two brothers attempted to reconcile, but eventually the division led to a war between the two brothers known as the Saxon Brother War (German: Sächsischer Bruderkrieg). The Saxon Brother War began in 1446 and lasted for five years, until the Peace of Naumburg was negotiated in 1451. Following the peace, the subsequent Treaty of Eger in 1459, and the deaths of Frederick II and Wilhelm III, the two sons of Frederick II eventually gained control of the land of both their father and Wilhelm III.

The House of Wettin and its line of Saxon princes gained a large amount of land over the years mainly through inheritance, including the Landgraviate of Thuringia, the Margraviate of Meissen, the Duchy of Saxony and the Electorate of Saxony. Frederick I was the Elector of Saxony and Margrave of Meissen and ruled over all of the lands except for the lands in Thuringia. Frederick I's cousin Frederick of Thuringia was Landgrave of Thuringia and ruled over those lands. Frederick I, had seven children including four sons. He ruled over his lands until his death in 1428. With his death, his four sons Frederick, William, Henry, and Sigismund took control of his land. Henry then died in 1435, and Sigismund was forced to renounce his claims and later became the Bishop of Würzburg in 1440. This led to only two sons, Frederick and William, now ruling over their family's land. As the oldest, Frederick held the Electorate of Saxony and some land around Wittenberg in his own right, while he controlled the remainder of the land jointly with William. This continued peacefully and without serious incident until 1440. In 1440, Frederick of Thuringia died childless and the two brothers inherited extensive land within Thuringia as well as the title of Landgrave of Thuringia.

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