which considerably weakened the political and economic importance of the Habsburg lands. It was not until 1453 in the reign of Frederick V the Peaceful (1457–1493) that the country (at least the core territories) would be finally united again. Rudolph IV's brothers Albert III the Pigtail and Leopold III the Just quarreled ceaselessly and eventually agreed to split the realm in the Treaty of Neuberg in 1379, which was to result in further schisms later. Altogether this resulted in three separate jurisdictions. Lower Austrian Territories or Niederösterreich (Upper and Lower Austria) Albertinian Line – extinct 1457, passed to Leopoldians Inner Austrian Territories or Innerösterreich (Styria, Carinthia, Carniola, and the Austrian Littoral of Istria and Trieste) Leopoldian Line then Elder Ernestine Line 1406–1457, continuing as Archduchy of Austria. Further Austrian Territories or Vorderösterreich (Tyrol, Vorarlberg and the Swabian and Alsatian territories) Leopoldian Line then Junior Tyrolean Line 1406–1490, passed back to Leopoldians Albertinian line (1379–1457) In 1379 Albert III retained Austria proper, ruling till 1395. He was succeeded by his son Albert IV (1395–1404) and grandson Albert V (1404–1439) who regained the imperial throne for the Habsburgs and through his territorial acquisitions was set to become one of the most powerful rulers in Europe had he not died when he did, leaving only a posthumous heir, born four months later (Ladislaus the Posthumous 1440–1457). Instead it was Ladislaus' guardian and successor, the Leopoldian Frederick V the Peaceful (1457–1493) who benefited. The Albertinian line having become extinct, the title now passed back to the Leopoldians. Frederick was so aware of the potential of being the young Ladislaus' guardian that he refused to let him rule independently upon reaching majority (12 in Austria at the time) and had to be forced to release him by the Austrian Estates (League of Mailberg 1452). Leopoldian line (1379–1490) Leopold III took the remaining territories, ruling till 1386. He was succeeded by two of his sons jointly, William the Courteous (1386–1406) and Leopold IV the Fat (1386–1411). In 1402 yet another split in the Duchy occurred, since Leopold III had had four sons and neither Leopold IV or William had heirs. The remaining brothers then divided the territory. Ernest the Iron (1402–1424) took Inner Austria, while Frederick IV of the Empty Pockets (1402–1439) took Further Austria. Once William died in 1406, this took formal effect with two separate ducal lines, the Elder Ernestine Line and Junior Tyrolean