Sigismund I the Old (
Polish Zygmunt I Stary;
Lithuanian Žygimantas II Senasis; 1 January 1467 – 1 April 1548) of the
Jagiellon dynasty reigned as King of
Poland and Grand Duke of
Lithuania from 1506 until 1548. Earlier, Sigismund had been invested as
Duke of Silesia.
The son of King Casimir IV Jagiellon and Elisabeth of Austria, Sigismund followed his brothers John I of Poland and Alexander I of Poland to the Polish throne. Their elder brother Ladislaus II of Hungary and Bohemia became king of Hungary and Bohemia. Sigismund was christened as the namesake of his mother's maternal grandfather, Holy Roman Emperor Sigismund, who had died in 1437.
Sigismund faced the challenge of consolidating internal power in order to face external threats to the country. During Alexander's reign, the law Nihil novi had been instituted, which forbade Kings of Poland from enacting laws without the consent of the Sejm. This proved crippling to Sigismund's dealings with the szlachta and magnates.
Despite this Achilles heel, he established (1527) a conscription army and the bureaucracy needed to finance it.