The Prince Bishops
Durham Castle was built in 1072 by Waltheof, Earl of northumberland, on the orders of William the Conquerer, to defend Northern England from the Scots and to control the local population.
The castle was soon handed over by the King to the first Bishop of Durham (William Walcher) and who had a number of unique powers. These Bishops are known as the Prince-Bishops.
The Prince Bishops of Durham were among the most powerful and wealthy men in the country, much more so than normal Bishops. They held both religious and political authority and could:
Impose and collect taxes.
Mint their own coins.
Raise an Army.
Hold their own courts.
As long as he remained loyal to the King of England, the Prince Bishop could govern as a virtually automonous ruler, reaping the revenue from his territory but also remaining mindful of his role of protecting England’s northern frontier.