Frederick II (; 25 April 1211 – 15 June 1246), known as Frederick the Quarrelsome (Friedrich der Streitbare), was Duke of Austria and Styria from 1230 until his death. He was the fifth and last Austrian duke from the House of Babenberg, since the former margraviate was elevated to a duchy by the 1156 Privilegium Minus. He was killed in the Battle of the Leitha River, leaving no male heirs. Family Born in Wiener Neustadt, Frederick was the second surviving son of the Babenberg duke Leopold VI of Austria and Theodora Angelina, a Byzantine princess. The death of his elder brother Henry in 1228 made him the only heir to the Austrian and Styrian duchies. His first wife was Byzantine princess Eudokia Laskarina, (referred to as Sophia), a daughter of emperor Theodore I Laskaris and his first wife Anna Komnene Angelina. They were divorced by 1222. Frederick secondly married Agnes of Merania in 1229, an heiress of the extinct noble House of Andechs whose dowry included large possessions in Carniola and the Windic March. From 1232 Frederick styled himself Dominus Carniolae ("Lord of Carniola"). However, the marriage was dissolved due to childlessness in 1243. Reign Frederick succeeded his father in 1230. Proud of his Byzantine descent, the young duke soon was known as the Quarrelsome because of his harsh rule and frequent wars against his neighbors, primarily with Hungary, Bavaria and Bohemia. Even the Austrian Kuenring ministeriales, which had so far been faithful to the ruling house, started an insurgency as soon as his reign began. According to the Weltchronik of Jans der Enikel, Frederick had gone to the court of Emperor Frederick II by his summon, leading a procession of 200 knights wearing the triband colors of Austria. When he approached the Emperor, he was enthusiastically invited—by both command and request of Emperor Frederick—to eat bread with him. The Duke refused, stating he brought his own gold. But the Emperor insisted without prevailing. Thus instead he ordered that no one in the town sell the Duke firewood for his kitchen. Duke Frederick instead sought a house to buy and when the Emperor learned of this, forbade it. Duke Frederick then instructed his marshal to go out late at night and buy some nuts so that his food could be prepared. Duke Frederick had impressed the Emperor so much that he allowed him the sale of firewood and whatever he