In 609 Pope Boniface IV obtained leave from the Byzantine Emperor Phocas to convert the Pantheon in Rome into a Christian church, a practice similar to that recommended eight year earlier by Pope Gregory I to Mellitus regarding Anglo-Saxon holy places, in order to ease the transition to Christianity. According to Willibald's "Life of Saint Boniface", about 723, the missioner cut down the sacred Donar's Oak and used the lumber to build a church dedicated to St. Peter. Around 744, Saint Sturm established the monastery of Fulda on the ruins of a 6th-century Merovingian royal camp, destroyed 50 years earlier by the Saxons, at a ford on the Fulda River.