Rudolph I. Of Hapsburg, emperor of Germany, founder of the imperial house of Austria, son of Count Albert IV. of Hapsburg, born in the Breisgau, May 1, 1218, died in Ger-mersheim, July 15, 1291. He was brought up at the court of his uncle the emperor Frederick II., under whom he served in the wars in Italy. On the death of his father in 1240, he succeeded to the landgraviate of Upper Alsace, the burgraviate of Rheinfelden, and with his brother to the county of Hapsburg. He wrested additional territory from his relatives and others, and in 1245 married a daughter of Burchard, count of Hohenberg, who brought him valuable possessions. He distinguished himself in several wars, and acquired so high a reputation for justice and prowess that he was chosen by many cities as their protector and the leader of their armies. In 1264 he became chief magistrate of Zürich, and was involved in several conflicts, which generally terminated in his favor. The most bitter of these was with the bishop of Basel, and Rudolph was besieging that city in 1273 when he was unanimously chosen to the throne of Germany in preference to Alfonso of Castile and Ottocar of Bohemia. Basel immediately opened its gates, in spite of the angry remonstrances of the bishop.

Rudolph strengthened himself after his coronation at Aix-la-Chapelle (Oct. 28) by the marriage of his two daughters, Matilda and Agnes, to Louis, duke of Bavaria, and Albert, duke of Saxony, and by a concordat with Pope Gregory X., who persuaded Alfonso of Castile to recognize Rudolph, while Duke Henry of Bavaria and King Ottocar of Bohemia were speedily overcome by him. Ottocar, after violating a truce, fell in battle on the Marchfeld, Aug. 26, 1278. Rudolph restored Bohemia and Moravia to Wenceslas, son of Ottocar, but retained Austria, Styria, and Carniola for his own sons. He now established order and tranquillity in his dominions, put an end to the depredations of the feudal barons by sentencing many of them to death and demolishing their strongholds, and passed so many new decrees that he was called lex animata, "the living law." Under him German was substituted for Latin in official documents. Rudolph also engaged in a successful war with the count of Savoy, but was unsuccessful in 1288 against the city of Bern. He restored order in Bohemia, delivering the young king Wenceslas II. from his captivity, and marrying him to one of his daughters. He was greatly mortified at the refusal of the diet of Frankfort in 1291 to choose his son Albert as his successor.

He set out for Spire, but died on the way, and was succeeded on the imperial throne by Adolphus of Nassau. - See Geschichte Rudolfs von Habsburg, by Schönhuth (2 vols., Leipsic, 1843-4).