The succession of bishops in Cologne is traceable, except for a gap covering the troubled 5th century, from A.D. 313, when the see was founded. It was made the metropolitan see for the bishoprics of the Lower Rhine and part of Westphalia by Charlemagne, the first archbishop being Hildebold, who occupied the see from 785 to his death in 819. Of his successors one of the most illustrious was Bruno (q.v.), brother of the emperor Otto I., archbishop from 953 to 965, who was the first of the archbishops to exercise temporal jurisdiction, and was also "archduke" of Lorraine. The territorial power of the archbishops was already great when, in 1180, on the partition of the Saxon duchy, the duchy of Westphalia was assigned to them. In the 11th century they became _ex-officio_ arch-chancellors of Italy (see ARCHCHANCELLOR), and by the Golden Bull of 1356 they were finally placed among the electors (_Kurfürsten_) of the Empire. With Cologne itself, a free imperial city, the archbishop-electors were at perpetual feud; in 1262 the archiepiscopal see was transferred to Brühl, and in 1273 to Bonn; it was not till 1671 that the quarrel was finally adjusted. The archbishopric was secularized in 1801, all its territories on the left bank of the Rhine being annexed to France; in 1803 those on the right bank were divided up among various German states; and in 1815 by the congress of Vienna, the whole was assigned to Prussia. The last archbishop-elector, Maximilian of Austria, died in 1801.
In Archbishop Hildebold's day Cologne was still contained by the square of its Roman walls, within which stood the cathedral and the newly-founded church of St Maria (known later as "im Capitol"); the city was, however, surrounded by a ring of churches, among which those of St Gereon, St Ursula, St Severin and St Cunibert were conspicuous. In 881 Norman pirates, sailing up the Rhine, took and sacked the city; but it rapidly recovered, and in the 11th century had become the chief trading centre of Germany. Early in the 12th century the city was enlarged by the inclusion of suburbs of Oversburg; Niederich and St Aposteln; in 1180 these were enclosed in a permanent rampart which, in the 13th century, was strengthened with the walls and gates that survived till the 19th century.
