Sigismund I of Poland was born on the 1 January 1467 to Casimir IV of Poland and Elizabeth of Austria. He was their fifth son, but the eldest brother Saint Casimir died before Casimir IV, whilst the second brother, Vladislaus, was elected King of Hungary and Bohemia and John and Alexander who had inherited Poland and Lithuania died childless, so in 1506 he became the King of Poland and Grand-Duke of Lithuania.