The changing alliances within the House of Habsburg that ensued after the divisions in the dynastic lines that took place in the late medieval period are difficult to make out. Duke Ernest’s claims initially posed only a further hindrance to an amicable settlement. Ultimately, though, he proved successful – in that he survived his rivals.
Ernest was the third son of Duke Leopold III, the founder of the Leopoldine line of the Habsburgs, and Viridis Visconti. After the early death of his father – Ernest was twelve years old at the time – he was initially placed under the guardianship of his eldest brother William. After the latter’s death in 1406 Ernest was granted rulership over the lands of Styria, Carinthia and Carniola but had to reign jointly with his elder brother Leopold IV.
According to the terms of the dynastic agreement, Ernest was also supposed to share in the regency of Austria with Leopold until Albrecht V, the heir to the Albertine Habsburg line, gained his majority. The agreement also stipulated that as soon as Albrecht gained his majority in 1411, the territories of the Leopoldine line should be divided between the brothers, with one brother receiving Styria and the other Carinthia and Carniola.
This provided constant potential for conflict as Leopold’s regency over Austria ensured a steady flow of revenue into his coffers, and Ernest wanted his share. The old saw that says when two people quarrel, a third rejoices is certainly pertinent here: because the brothers were unable to agree, the Estates and local rivals profited, in this case the counts of Cilli from Carniola, who rose from the ranks of country nobility to become princes of the Empire, and were dangerous rivals of the Habsburgs for sovereign rights in Carniola and Styria: parts of these two duchies threatened to become independent sovereign imperial territories.
The only thing the two brothers agreed upon was that Albrecht’s majority should be delayed as long as possible. This scheme was thwarted when their ward was abducted by Lower Austrian nobles and Albrecht declared in June 1411 that he would be assuming power himself in Austria forthwith.
Duke Ernest had lost influence in Austria but ultimately profited from this turn of events: his hated brother Leopold died of a stroke, embittered by the abduction of Albrecht, leaving Ernest as sole ruler at least over Styria.