However, only Louis the Bavarian, co-elected with Saxe-Lauenburg's vote, finally asserted himself as emperor after the 1322 Battle of Mühldorf by the Treaty of Trausnitz on March 13, 1325. As an obvious opponent, Duke Rudolph I failed with his claims to Brandenburg after the line of his Ascanian cousins became extinct in 1319: King Louis IV seized the margraviate and enfeoffed his son Louis V instead. Rudolph I in turn allied with the rivaling House of Luxembourg. He supported Count Charles IV of Luxembourg as anti-king to Louis IV and on that account exclusively received the Saxon electoral dignity with the Golden Bull of 1356, thus slighting Saxe-Lauenburg. Saxe-Wittenberg thereupon came to be known as the Electorate of Saxony ("Kursachsen").