Josip Jelačić was born on October 16, 1801 in Petrovaradin, where his father Franjo was sub-marshal of the Slavonian Military Frontier. He was born into a noble family whose members were distinguished warriors, high military commanders, statesmen, priests, educators, benefactors and writers. His mother Ana Portner was also from a noble family, and in addition to Josip, she gave birth to two more sons, Jura and Antun, and a daughter, Cecilia.
Barbara of Celje was born most probably in 1392 as the daughter of Herman II of Celje and Countess Ana von Schaunberg. Her father was one of the most powerful feudal lords in the Hungarian-Croatian kingdom with large estates in Slovenia and Croatia. He was also a big friend of the then King Sigismund of Luxembourg, whom he even saved by helping to escape the catastrophic defeat of the Ottomans at Nicopolis in 1396. After the death of his first wife Maria Sigismund, he chose the then minor Barbara as his future wife. They married in Krapina in 1405.