Treaty of Rheinfelden
This article does not cite any sources. (December 2009) (Learn how and when to remove this template message)
Rudolph of Habsburg had been chosen King of the Romans in 1273 and had defeated his rival Ottokar II of Bohemia who was killed at the 1278 Battle on the Marchfeld. Ottokar's son Wenceslaus II retained the Bohemian Kingdom, while Ottokar's estates in Austria, Styria, Carinthia and Carniola fell back to the Holy Roman Empire.
King Rudolph had reached an agreement with the Prince-electors to award these territories to his sons and at the Diet of Augsburg in 1282 Albert I and his brother Rudolph II "jointly and severally" received Austria, Styria, Carniola and the Windic March. However in 1286 Meinhard II of Gorizia-Tyrol became Duke of Carinthia as recompensation for supporting King Rudolph against Ottokar and also retained Carniola and the Windic March as a fief.
Deviating from these decisions the Rheinfelden Treaty set down the primogeniture order: then eleven-year-old Duke Rudolph II had to waive all his rights to the thrones of Austria and Styria to the benefit of his elder brother Albert I. According to the terms of the agreement, Rudolf should receive some territories in Further Austria in return but was never compensated until his death in 1290. This fact induced his son John Parricida to murder Albert in 1308.
The adoption of the primogenitur right crucially strengthened the Habsburg influence within the Holy Roman Empire as it allowed the dynasty to constitute a compact allodial territory (Hausmacht) it could rely on. It nevertheless did not prevent the partition by the 1379 Treaty of Neuberg.