duke of upper Bavaria (from 1294) and of united Bavaria (1340–47), German king (from 1314), and Holy Roman emperor (1328–47), first of the Wittelsbach (Wittelsbach, House of) line of German emperors. His reign was marked by incessant diplomatic and military struggles to defend the right of the empire to elect an emperor independently of the papacy, to consolidate his own position, and to improve the status of his family.

As the younger son of Louis II, count Palatine and duke in Upper Bavaria, Louis had no claim to the crown by birth. On his father's death in 1294, the 11-year-old boy was made a ward of his brother Rudolf, who was then 20, and of his mother, Mechthild, a Habsburg and a daughter of King Rudolf I. Louis immediately found himself involved in high politics; his brother took the side of King Adolf of Nassau and his mother that of her brother, Albert I of Austria, who was attempting to depose Adolf. Keeping her son out of Munich, she sent him to her brother's court in Vienna, where he was reared, together with his Habsburg cousins, Frederick and Leopold. This circumstance no doubt had a lasting effect on Louis, though he never let political decisions be influenced by family ties. Albert's victory over Adolf of Nassau at Göllheim (July 2, 1298) allowed Louis to assume the share in the government that was his by law but that his older brother had hitherto withheld from him. The rivalry between the brothers, which had flared up again after the assassination of King Albert (1308), ended in 1310 with a partition of territories, which Louis was able to impose on the strength of being the guardian of his Lower Bavarian cousins. But the traditionally anti-Austrian attitude of Lower Bavaria led to a quarrel with the Habsburgs (Habsburg, House of). Having assured himself of his brother's goodwill by means of a compromise (June 21, 1313), Louis gained a decisive victory over the Habsburgs at Gammelsdorf (November 9), while the succession to the German crown, fallen vacant with the emperor Henry VII's unexpected death on August 24, was still the subject of negotiations.

The empire had become an elective monarchy, but counts no longer figured among the candidates. The houses of Habsburg and Luxembourg (Luxemburg), risen to the rank of major German powers as a result of acquiring Austria (1282) and Bohemia (1310), respectively, contended for the throne; had it not been divided into warring lines, the House of Wittelsbach might have been a third contender. On the strength of his victory, Louis, in 1314, became the candidate of the Luxembourgs, who had failed to gain the crown for John of Bohemia, the late emperor's son. The Habsburgs, however, would not acknowledge Louis, though he was grandson of King Rudolf (Rudolf I); in the double election of Oct. 19–20, 1314, Louis gained little advantage from the fact that his claims were rather more substantial than those of the anti-king, Frederick III (Frederick (III)) of Austria, crowned on the same day, November 25. Military successes enabled Louis to wrest exclusive control over Upper Bavaria and the Rhenish Palatinate from his brother, who had voted against him; but a permanent settlement with the latter's descendants could be made only after the death of Rudolf, his widow Mathilde of Nassau, and his oldest son, Adolf. The dynastic Compact of Pavia (1329), dividing the House of Wittelsbach into a Bavarian and a Palatinate line, enabled Louis to gain the latter line's support in matters of imperial policy. He failed, however, to achieve a lasting understanding with his Lower Bavarian cousins; that conflict was not settled until this line became extinct in 1340.

Louis's most pressing problem was the struggle with the Habsburgs. The decisive battle was fought on Sept. 28, 1322, at Mühldorf, where Louis gained victory, taking prisoner King Frederick with his brothers. By April 1323 he could risk investing his oldest son, Louis, still a minor, with the Margravate of Brandenburg, which had been in abeyance since 1319. Territorial aspirations motivated the conclusion of a hereditary alliance with the House of Wettin as well as Louis' second marriage, to Margaret of Holland (1324), which in 1345 led to the accession of Holland and its dependencies. These successes did not sit well with John of Bohemia, who refused to be pacified either by the donation of Upper Lusatia in 1320 or by the marriage of Duke Henry the Elder of Lower Bavaria with a Luxembourg the following year, or by the acquisition, by way of collateral, of the Egerland. Luxembourg finally allied itself with France, and this move, in turn, led to an increased hostility toward Louis on the part of the Pope, who was wholly under French influence.

Pope John XXII had taken advantage of the contest for the crown of Germany to appoint Robert of Naples imperial vicar in Italy vacante imperio (in the absence of a Holy Roman emperor) and to threaten the Italian Ghibellines with heresy proceedings. When Louis's own imperial vicar forced the Pope and Robert to raise the siege of Milan, the heresy proceedings were extended to Louis himself, who was excommunicated in March 1324. This interdiction, never lifted, exposed Louis' adherents to a conflict of conscience while providing his enemies with a convenient excuse for disobedience. In the eyes of the Curia and of his other enemies, he was thenceforth merely Ludovicus Bavarus, Louis the Bavarian, by which name he lives on in history.

Louis hit back with several proclamations of his own, notably the so-called Sachsenhausen Appellation of May 22, 1324, in which the charge of heresy was turned against the Pope. The argumentation ill-advisedly dealt with constitutional problems touching on the empire as well as with doctrinal points. Louis quickly acknowledged this as a mistake and softened its effect, but at this time the Austrians also joined the alliance of France and Luxembourg (July 27, 1324). Louis broke up the hostile combination by agreeing to share the rule with his prisoner Frederick; even so, he overcame Duke Leopold's objections only by further agreeing (Jan. 7, 1326) to abdicate altogether, provided that the Pope gave his approbation to Frederick's sole rule. There was little likelihood of that because the Curia was interested in perpetuating the rivalry for the German crown. Its reaction proved to Frederick that he had been callously used; he now became a loyal co-ruler with Louis.

When Duke Leopold died in February 1326, Louis boldly opposed the Pope in Italy itself. Supported by the Ghibellines, he accepted the iron crown of Lombardy in Milan (May 31, 1327) and the imperial crown in Rome (Jan. 11, 1328), offered by the representatives of the Roman populace. This unusual move could be considered an emergency measure because the Pope had refused to crown the designated emperor, declaring him a heretic on purely political grounds.

Louis let himself be persuaded to depose the Pope formally by a decree of April 18, 1328, and to countenance the appointment of an antipope whose incompetence furnished John XXII with an easy triumph. Moreover, Louis' forces were insufficient to subjugate Robert of Naples or to institute a stable order in Italy, for which he lacked the necessary prerequisite of a firm hold on Germany. Turning to the north again, he celebrated Christmas of 1329 in Trent, whence he had departed for Italy in February 1327.

King Frederick died on Jan. 13, 1330. The problem of shared rule was thus solved. Yet Louis' German enemies had not been idle. John of Bohemia (John) had arranged the marriage of his younger son, John Henry, with Margaret, the heiress of Carinthia-Tirol, in 1330. This caused Louis to enter into a secret covenant with the Habsburgs regarding the partition of this strategically important inheritance (May 31, 1331). He thus encircled John of Bohemia, forcing him to withdraw from Italy, where he had ensconced himself in the guise of an imperial vicar. In order to confuse his enemies, Louis issued a new decree of abdication, hedged with countless provisos, on Nov. 19, 1333; this time he proposed to renounce the throne in favour of his Lower Bavarian cousin Henry. The death of Duke Henry of Carinthia-Tirol in 1335 compelled Louis to invest the Habsburgs with Carinthia, by way of carrying out his part of the secret compact; he also granted them southern Tirol in order to save at least the northern part for himself. But the Habsburgs, in their eagerness to secure Carinthia, concluded an agreement behind his back with Luxembourg, which thus acquired the whole of the Tirol. As a result, the influential archbishop of Mainz came over to Louis' side (June 29, 1337), and Edward III of England made a treaty with him (August 26), thus proving that Louis was a desirable ally on the international plane.

The Germans, tired of the incessant quarrels over the crown, were disconcerted by the Pope's intransigence. Through their city magistrates and other representatives, they pressed for legitimization of Louis' rule and the rejection of papal interference. When Louis issued a statement of principle regarding the accession to the imperial throne before the Frankfurt Diet (Fidem catholicam of May 17, 1338), he had the support not only of the cities but also of the empire's ecclesiastical lords. He relied upon this support in promulgating a basic electoral law (Licet juris) in Frankfurt (August 3) and again in Coblenz, where he met the King of England and bestowed on him an imperial vicarate on the Lower Rhine. The promulgation of that law, however, remained an empty gesture because the electoral princes, while assembled at Rhens on July 16, had rejected the Pope's claims without declaring themselves in favour of Louis and withheld their approval. The conflict over the crown and the charge of heresy thus continued to smolder. By isolating John of Bohemia and issuing a formal waiver of his own claims to the Tirol, Louis managed nonetheless to force John to renounce all claims to Italy, to declare himself a vassal, and to acknowledge Louis emperor in 1339.

Seeing that the entire clergy of the empire, except for the border bishoprics of Liège and Cambrai, had submitted to his rule and that the English held out the prospect of subsidies, Louis had reason to hope that he could confront the French in battle and thereby make the Pope yield. When Edward III declared war on France on Sept. 1, 1339, and had himself acknowledged as king of France in Ghent on Jan. 27, 1340, Louis was in a position to arbitrate between England and France. But the Tirolean question spoiled everything. In November 1341 Margaret expelled her Luxembourg husband; whereupon Louis, declaring that the marriage had not been consummated and was therefore void, married her with ill-considered haste to his widowed son, Louis of Brandenburg, on Feb. 10, 1342. This created an unfavourable impression throughout the empire. Worse, it led to the final rupture with Luxembourg and to Charles of Moravia, son of John of Luxembourg, declaring himself a candidate for the imperial crown now that the King of France, at war with England, was eliminated as a pretender. Louis vainly attempted to propitiate the Luxembourgs by the cession of Lower Lusatia and by the offer of one of his daughters in marriage. They negotiated with him but at the same time encouraged the new, intensely nationalistic French pope to renew the heresy proceedings against him and to demand a new election (August 1343). Once more Louis countered by offering to abdicate, this time in favour of his son, Louis of Brandenburg-Tirol (September 1343). The Luxembourgs maintained the negotiations until Charles of (Charles IV) Moravia, who had granted excessive concessions to the Pope, gained all electoral votes except the two of the House of Wittelsbach and thus was elected king (July 1346). Preparing himself for the war that had become inevitable, Louis died of a heart attack while bear hunting near Munich in the autumn of 1347.

Louis had wanted to raise his family to a royal status like that of the houses of Habsburg and Luxembourg. But he failed to achieve the major prerequisite—the welding of his family into a uniform body motivated by a single political will. He strove for this unity with all the diplomatic and juridical means at his disposal, and the Upper Bavarian law code of 1346 (first formulated about 1335) remains a monument to these efforts. For, while Charles IV did what he could to erase Louis' memory within the empire, Charles's famous edict, the Golden Bull (Golden Bull of Emperor Charles IV) of 1356, represents only the final codification of fundamental imperial laws that had actually evolved under Louis. This codification enabled the empire to stand up to the juridically minded church of Avignon.

Louis possessed courage and tenacity without being rigid. He won men over by a jovial and chivalrous demeanour, and his suppleness, coupled with diplomatic skill, charmed them even as a certain mercurial quality made him appear unfathomable. He was a political man, whose guiding principle remained the honor imperii. Even in his darkest hours he brooked no interference with the imperial rights. It would be unfair to judge him solely by the yardstick of success. It was Louis' fate to repeatedly come up with inadequate resources against adversaries who were talented and powerful.

king of France from 936 to 954 who spent most of his reign struggling against his powerful vassal Hugh the Great.

When Louis's father, Charles III the Simple, was imprisoned in 923, his mother, Eadgifu, daughter of the Anglo-Saxon king Edward the Elder, took Louis to England. He was recalled to France in 936 and crowned on June 19 at Laon by Artand, archbishop of Reims, who became Louis's chief supporter against Hugh the Great. Louis proved not to be the puppet monarch that Hugh had anticipated; he even moved from Paris to Laon to avoid Hugh's influence. In 939 he married Gerberga, the sister of King Otto I, the future Holy Roman emperor. When Hugh and Herbert of Vermandois seized Reims and attacked Laon in 940, Louis valiantly defended his city; but because of Louis's earlier interference in Lorraine the German king, Otto I, sent aid to the rebels. Louis appeared to be totally defeated in 941, but he made peace with Otto in November 942 at Vise on the Meuse, and Hugh and he were reconciled after Herbert, Hugh's chief supporter, died in 943.

In 945, while intervening in Norman politics, Louis was captured and handed over to Hugh, who imprisoned him for a year until Louis surrendered his main base of Laon. On his release, Louis closely allied himself with Otto to retake Reims in 946. In 949 Louis again received control of Laon, and Hugh, excommunicated by French and German synods and by the Pope, made a peace in 951 that lasted until Louis's death.

East Frankish king, the last of the East Frankish Carolingians. During his reign the country was ravaged by frequent Magyar raids, and local magnates (the ancestors of the later ducal dynasties) brought Bavaria, Franconia, Swabia, and Saxony under their sway.

The only son of the East Frankish king Arnulf, Louis was declared heir to the kingdom in 897 and, after Arnulf's death (899), was crowned king in 900. Later that year a party of Lotharingians, after defeating their king, Zwentibold (Louis's half brother), in an uprising, acknowledged Louis as their sovereign.

Although in theory the boy king was himself the ruler, the government was in fact controlled by Archbishop Hatto I of Mainz and by Salomo, bishop of Constance (Konstanz). The kingdom was, however, too weak to check the raids of the Magyars, which became increasingly frequent after 900. In 910 they defeated a large royal army near Augsburg. Louis's death the following year ended the East Frankish Carolingian line.