Elizabeth of Austria was the wife of King Casimir IV of Poland and thus Queen of Poland and Grand Duchess of Lithuania. Orphaned at an early age, she spent her childhood in the court of Frederick III, Holy Roman Emperor. As one of the three surviving grandchildren of Emperor Sigismund, she had a strong claim to the kingdoms of Hungary and Bohemia. That made her an attractive bride for a Polish prince. Polish nobility, seeking to increase Polish influence in Hungary and Bohemia, pursued marriage with Elizabeth since she was born and finally succeeded in 1454. Her marriage to Casimir was one of the most exemplary royal marriages in Poland. She gave birth to thirteen children, eleven of whom survived to adulthood. Four of her sons were crowned as kings.
Elisabeth was the daughter of Albert II of Germany, Archduke of Austria, and his wife Elizabeth of Luxembourg, daughter of Emperor Sigismund. The exact date of her birth is unknown and has been variously provided between 1436 to early 1439. Her elder brother was born in February 1435. Polish chronicler Jan Dugosz mentioned that Polish envoys traveled to Vienna in autumn 1436 to negotiate with Emperor Sigismund a marriage between his granddaughters, Anne and Elisabeth, who were considered heiress to the thrones of Bohemia and Hungary, and Polish princes Wadysaw and Casimir. While the negotiations ended without a decisive agreement, they allowed historians to conclude that Elisabeth was born in the first half of 1436.
Source: Wikipedia