An exempt see, comprising the Prussian province of Hanover east of the Weser, besides the Duchy of Brunswick. It owed its foundation to Emperor Louis the Pious. His father had originally selected for an episcopal see the village of Elze (Aulica), but we are told by the legend that Louis was influenced by a miracle to choose the present cathedral site. He erected on this spot the first chapel in Germany dedicated to the Mother of God. The precise year in which this see was founded is not known; the date varies according to different accounts from 814 to 822. The first bishop was Gunthar (about 815-834). The surrounding dioceses were, on the north, Verden, on the east, Halberstadt, on the west, Minden and Paderborn, and, on the south, Mainz, of which it was suffragan. Rich donations were made to Hildesheim, some of them by the German kings themselves. Immunities and the prerogatives of independent jurisdiction, together with feudal sovereignty, soon brought it a large measure of prosperity and power. The period covered by the administrations of Bishops St. Bernward (993-1022), St. Godehard (1022-1038), and Hezilo (1045- 1079) was one of special lustre. To Bernward's artistic tastes are due the famous bronze doors of the cathedral, the Christus- column, the Bernward cross, also the beautiful church of St. Michael, still preserved, the western crypt of which contains the tomb of Bernward. The Abbey of Gandersheim, renowned as the home of Hroswitha, the famous Latin poetess, was the occasion of a dispute between Hildesheim and Mainz which lasted many years, but was finally settled in favour of the former. Hildesheim obtained its political independence by the severe feud with Henry the Lion.

In 1221 Bishop Conrad II, one of the strongest personalities in thirteenth-century Germany, was invested with princely authority, and in 1235 his authority as territorial lord was recognized at Mainz. But he found the exercise of his ecclesiastical and territorial sovereignty restricted by the corporate independence of the town of Hildesheim, which endured until the middle of the thirteenth century (earliest municipal constitution, 1249), and of the cathedral chapter; the latter, thanks to the "Great Privilege" of Bishop Adelog, maintained since 1170 a far-reaching right of participation in the government; the year 1216 saw the first "Wahlkapitulation"; while in 1221 all participation in the selection of a bishop was finally taken away from the great officers, or Ministeriales, of the see. The close combination of spiritual and temporal authority meant for the bishop countless sources of disorder and of violent conflict with domestic and foreign adversaries, chief among whom were the Guelphs. The victory of Gernard over Duke Magnus of Brunswick and his ally at Dinklar in 1367 is well known. These incessant wars and agitations paralysed religious growth. Bishop Magnus (1424-52) having determined to restore domestic concord, entered into various treaties with neighbouring principalities and towns for the safeguarding of peace, and took up energetically the reform of internal religious life, which popes and councils had so long advocated. Johannes Busch, Provost of the Augustinians, laboured efficiently for monastic reforms; and about this time the Benedictines of Bursfeld began their reformatory work in the diocese. Cardinal Nicholas of Cusa arrived at Hildesheim in 1451. But the reforms were not lasting. The old troubles of the see, war and internal feuds, broke out anew and with greater violence than before, until at length the once flourishing see fell a victim to what is known as the "great diocesan war" (grosse Stiftsfehde). Of its eleven districts, with twenty-seven counties and twenty-one castles, only the three districts of Peine, Steuerwald, and Marienburg, the so-called "small diocese", were left to the See of Hildesheim by the compact of Quedlinburg, in 1523; the "large diocese" fell into the hands of the victorious Guelphs and the once great power of the Bishops of Hildesheim passed away. Internal conflicts prepared the way for the Reformation.

Bishop Valentine strove to strengthen the ancient Faith among his people by calling a diocesan synod in 1539, at which he promulgated a number of decrees; but in vain. In 1542 the city of Hildesheim adopted the new doctrines, and the Protestant Dukes of Brunswick introduced the Reformation into the "large diocese". Catholicism was vigorously defended by the auxiliary bishop, Balthasar, from the pulpit of the cathedral, but the city government had recourse to measures of violence. Amid these disturbances an old man of ninety was erecting in the cathedral one of the handsomest monuments of the early German Renaissance. This was Canon Arnold Fridag, who put up the magnificent lectern (Lettner) with its rich pictorial ornament. Meanwhile the see entered on the most critical period of its history, when a Lutheran prince, Duke Friedrich of Holstein, ascended the episcopal throne in 1551. His premature death saved the see from total disaster. Thanks to his truly Catholic successor, Burchard, the ancient Faith and the few remaining properties of the Church were preserved. The cathedral chapter, after his death, resorted to the only expedient available for ensuring the stability of the see and of the Catholic religion therein, by entrusting the small diocese to a powerful ecclesiastical prince. From 1573 to 1761, with but a short interruption, the bishops were chosen from the ducal House of Bavaria, which, in order more efficiently to combat the spread of Protestantism, kept other sees constantly under its control, among them Cologne itself. They also brought the Jesuits to Hildesheim at an early date.

By this time the Thirty Years War had brought manifold burdens and afflictions on the see. Even the cathedral was for a short time, in 1634, given over to the Lutheran worship by victorious enemies. The see continued to exist, however, though surrounded by Protestant territory. In 1643 the "large diocese", which had been lost in 1523, was regained, though all attempts to win back the population to the Catholic Faith was frustrated by the "Normal Year" article of the Treaty of Westphalia, i.e. what had been Protestant down to 1624 was in the future to remain so. The "large diocese" remained united to Hildesheim until, in 1803, "secularization" severed the prince's crown from the bishop's mitre, and suppressed the Catholic chapter and numerous monasteries and convents. In 1803 the see was given to Prussia as a secular principality. In 1807 it became part of the Kingdom of Westphalia under Jerome Bonaparte, and in 1813 it was incorporated with the Kingdom of Hanover. In 1824 the Bull "Impensa Romanorum Pontificum" gave its present form to this diocese, henceforth deprived of all temporal power, and brought within its jurisdiction all the scattered Catholics of the Kingdom of Hanover east of the Weser. In 1834 the Duchy of Brunswick was added. The new see has an area of about 540 square miles. The true restorer of the see was Bishop Edward Jacob, who by his apostolic zeal and self-sacrifice accomplished great results. He was aided by the personal goodwill of King George V of Hanover, as well as by the general upward movement of the Catholic Faith in Germany. He introduced the Franciscans and the Augustinians into the diocese, also the Sisters of Charity of St. Vincent de Paul, whom he summoned from Paderborn. The present bishop (since 1906) is Dr. Adolf Bertram. The diocese numbers (1908) 201,914 Catholics (without counting soldiers or the inmates of prisons). It is divided into 15 deaneries and contains 109 parishes, 25 Kuratien, 174 churches and chapels; the clergy numbers 233 secular priests, and 4 Augustinian, and 8 Franciscan monks. There are Ursuline nuns at Duderstadt, with 37 professed and 18 lay nuns, besides 8 novices; also Sisters of Charity of St. Vincent de Paul at Hildesheim (mother-house), with 35 establishments, numbering 308 professed nuns and 33 novices.

BERTRAM, Die Bischöfe von Hildesheim (Hildesheim, 1896); IDEM, Geschichte des Bistums Hildesheim, I (Hildesheim, 1899); IDEM, Die katholische Kirche unserer Zeit herausgegeben von der österr. Leogesellschaft, II (Munich, 1899-1902), 192 sq.; NEHER, in Kirchenlex., s. v.; DÖBNER, Studien zur hildesheim'schen Geschichte (1902); IDEM, Urkundenbuch der Stadt Hildesheim (Hanover, 1880-1901); JANICKE AND HOOGEWEG, Urkundenbuch des Hochstifts Hildesheim und seiner Bishöfe 4 vols. have already appeared (Hanover, 1896-1905); MARING, Diözesansynoden und Domherrn-General kapitel des Stifts Hildesheim (Hanover, 1905); IDEM, Die Kongregation der barmherzigen Schwestern vom hl. Vincenz von Paul in Hildesheim (Hildesheim, 1908); HILLING, Die römische Rota und das Bistum Hildesheim am Ausgange des Mittelalters, supplement VI of the Reformationsgeschichtliche Studien und Texte (Münster, 1908).

Joh. Maring.