Boniface left England, never to return, and took the gospel to the heathen tribes of Germany, where he had great success. He himself was created Bishop of Mainz, and he founded or restored dioceses in Bavaria, Thuringia, and Franconia. In his later years he worked with King Pepin the Short to reform the Frankish church, and then, over seventy years old, set out to evangelize Friesland (part of modern Holland) where he was set upon and murdered, on 5 June 754.

  He is buried at Fulda, near Frankfurt, in the monastery he founded himself, and is honoured as the apostle of Germany.