Sigismund (26 October 1427 – 4 March 1496), a member of the House of Habsburg, was Duke of Austria from 1439 (elevated to Archduke in 1477) until his death. As a scion of the Habsburg Leopoldian line, he ruled over Further Austria and the County of Tyrol from 1446 until his resignation in 1490.
Biography
Sigismund (or Siegmund, sometimes also spelled Sigmund) was born at the Tyrolean court in Innsbruck; his parents were the Further Austrian duke Frederick IV of Austria and his second wife Anna of Brunswick, a daughter of the Welf duke Frederick I of Brunswick-Lüneburg. A minor upon his father's death in 1439, the Inner Austrian duke Frederick V, Sigismund's first cousin, acted as regent until 1446. Frederick, elected King of the Romans (as Frederick IV) in February 1440, exploited all opportunities to extend his influence over the Further Austrian lands. He also interfered in the Old Zürich War in order to regain the former Habsburg territories lost to the Swiss Confederacy, while the Tyrolean nobles urged him to cede the rule to Sigismund.
The mines of Tyrol remained an important source of revenue for Frederick and not until 1446, upon the end of his regency, Sigismund could accede to rulership over the Further Austrian (Vorderösterreich) possessions, which also included the Swabian territories of the Sundgau in southern Alsace, the Breisgau, and numerous smaller estates. His cousin had planned to marry him off to the French princess Radegonde, a daughter of King Charles VII the Victorious, however, she died in 1445. Sigismund, represented by Ludwig von Landsee, married Princess Eleanor of Scotland, the daughter of the Stuart king James I, on 8 September 1449, in an Augustinian church near Chinon.
Sigismund was able to acquire large parts of the former County of Bregenz (in present-day Vorarlberg) in 1451 and further estates in the Großwalsertal and Kleinwalsertal. Nevertheless, he had to cope with claims raised by Frederick's brother, Archduke Albert VI of Austria, and temporarily had to cede the rule over several Further Austrian territories to him. For much of his reign, he was engaged in disputes with Nicholas of Cusa, then Prince-bishop of Brixen and raised to Cardinal in 1449, for the control of the Tyrolean Eisack, Puster and Inn valleys. Sigismund sided with Nicholas' opponent Gregory of Heimburg and in 1460, when he marched against the bishop's residence at Bruneck Castle, he was excommunicated by Pope Pius II. Nicholas fled to Todi in the Papal States, but fell ill and died in 1464, before the archduke surrendered in order to receive the papal pardon.