Oleśnicki gained the upper hand again and pursued his long-term objective of Poland's union with Hungary. At that time, the Ottoman Empire embarked on a fresh round of European conquests and threatened Hungary, which needed the assistance of the powerful Polish–Lithuanian ally. In 1440, Władysław III assumed the Hungarian throne. Influenced by Julian Cesarini, the young king led the Hungarian army against the Ottomans in 1443 and again in 1444. Like Cesarini, Władysław III was killed at the Battle of Varna.