Saxe-Altenburg (German: Sachsen-Altenburg) was one of the Ernestine duchies of the House of Wettin.Altenburg was independent for most of the 1600s until 1672. This is when the last male ruler died. Because only men could rule the Ernestine duchies Altenburg began to be ruled by the Duke of Saxe-Gotha, who had married the last ruler’s daughter.