Ernest the Iron (1377 - 1424) was the Duke of Carinthia, Styria, and Margrave of Carniola from 1406 until 1424. Ernest was the youngest son of Duke Leopold III. After his father was killed in the Battle of Sempach in 1386, Ernest was placed under the guardianship of Archduke Albert III with the Pigtail of Austria. In 1401 he accompanied King Rupert of the Palatinate on his campaign in Italy. After his brother William the Courteous died in 1406, the lands he ruled were split and Ernest received Carinthia, Carniola, and Styria. With his brother Leopold he was the guardian of the infant Archduke Albert V, although the split guardianship started a civil war in 1407 which only ended in 1409.