Territorial development of power between secular and ecclesiastical rule in the Duchy of Westphalia at the end of the 12th century using the example of Archbishop Philipp von Heinsberg of Cologne

In the 12th century in particular, the archbishops of Cologne went hand in hand in establishing their rule and expanding their territory. The archbishops' territorial policy was to undergo a change into the 13th century, but nevertheless reached its peak. The second half of the 12th century in particular is regarded as the heyday of Holy Cologne. It was also the time when Cologne's city wall, which is still visible today, was extended enormously, as the city had already grown to its 19th century size in the 12th century. These developments were also of enormous relevance for high medieval Westphalia. The archbishop's territorial policy systematically encompassed the Rhenish (Vest Recklinghausen) and Westphalian possessions (Duchy of Westphalia).

It is primarily these Westphalian possessions, along with other regions, that will be the subject of this study, whereby the term Westphalia has a particular peculiarity. Today, the term ‘Westphalia’ is too often applied to the part of North Rhine-Westphalia that was only created after the Second World War. Until the High Middle Ages, the Westphalians were regarded as the Saxons who settled in the west. They were first mentioned as a group in the Frankish imperial annals in 775, but it was not the region of Westphalia we know today that was meant, but those core areas that had been transferred to the Archbishop of Cologne - Philip of Heinsberg - as the Duke of Westphalia in the 12th century.

In the context of this dissertation project, it is worth focussing on this dazzling metropolitan of Cologne. Held in high esteem by Emperor Frederick Barbarossa (1155-1190), he appointed Philip of Heinsberg (1167-1191) directly to the bishopric of Cologne after his predecessor Rainald of Dassel (1159-1167) had died in Italy. It proved particularly effective for Philip that tensions between Emperor Frederick Barbarossa and Duke Henry the Lion (1142/56-1180) had reached their highest level from 1177 onwards. The duke and cousin of the emperor had tempted his fate by once refusing to follow Barbarossa in the army. Philip of Heinsberg went down in history as the driving force behind the moral opposition and played a decisive role in ensuring that the Gelnhausen Charter marked the end of the old tribal duchy of Saxony. Heinrich was stripped of his duchies of Bavaria and Saxony. The Archbishop of Cologne received the duchies of Westphalia and Engern from the Emperor in return for his loyalty. These were added to his previous possessions and made him the most powerful prince in north-west Germany. From then on, Philip was to carry the crosier of Cologne for a whole decade and at the same time utilise his increase in power in a planned manner.

The question of the extent to which Philip of Heinsberg redefined his office in the direction of a territorial ruler, in particular through the judgement of Gelnhausen, which has not yet been explicitly raised in research, is investigated. The principles and maxims of his politics are analysed and the maxims according to which the Archbishop of Cologne acted are then highlighted. The criterion applied is whether there are systematic indications of regional intensifications of Philip's influence. As fundamental and seminal problems of territorial politics in the second half of the 12th century have only been dealt with marginally up to now, this study is intended in particular to explore the development of territorial power with regard to the opportunities available at this time, which Philip utilised in a concentrated manner.

The study is based on the analysis of a broad source base of both documentary and historiographical records. With regard to the subject of this study, Philip of Heinsberg and his territorial policy, a comprehensive monographic study has nevertheless long been necessary, as the works from the 19th and first half of the 20th century on the Archbishop of Cologne are largely outdated in terms of their state of research.

Supervisor of the project: Prof. Dr Brigitte Englisch