LOUIS IV., or V. (c. 1287-1347), surnamed the Bavarian, Roman emperor and duke of Upper Bavaria, was the second son of Louis II., duke of Upper Bavaria and count palatine of the Rhine, and Matilda, daughter of the German king Rudolph I. Having lost his father in 1294 he inherited, jointly with his elder brother Rudolph, Upper Bavaria and the Palatinate, but passed his time mainly at the court of the Habsburgs in Vienna, while his early experiences of warfare were gained in the campaigns of his uncle, the German king Albert I. He was soon at variance with his brother over their joint possessions. Albert taking the part of Louis in this quarrel, Rudolph promised in 1301 to admit his brother to a share in the government of Bavaria and the Palatinate. When Albert was murdered in May 1308, Louis became a candidate for the German throne; but his claim was not strongly supported. The new king, Henry VII., was very friendly with Rudolph, and as the promise of 1301 had not been carried out, Louis demanded a partition of their lands. Upper Bavaria was accordingly divided in 1310, and Louis received the north-western part of the duchy; but Rudolph refused to surrender any part of the Palatinate. In 1310, on the death of Stephen I., duke of Lower Bavaria, Louis undertook the guardianship of his two young sons. This led to a war between the brothers, which lasted till June 1313, when peace was made at Munich. Many of the nobles in Lower Bavaria, however, angered at Louis, called in the aid of Frederick I. (the Fair), duke of Austria; but he was defeated at Gammelsdorf on the 9th of November 1313, a victory which not only led to peace, but conferred considerable renown on Louis.