As a reward for his labours, Pope Gregory III., who received the papal crown in 731, raised Boniface in 732 to the dignity of missionary archbishop. This new authority enabled him to coerce refractory bishops who thwarted his efforts. Five years later, Boniface made his third and last visit to Rome, not now as an obscure missionary but with a great retinue of monks and converts. Once more returning to Germany with authority, he organised the Church in Bavaria (739) and thus curtailed ecclesiastical lawlessness by creating four bishoprics: Salzburg, Friesingen, Passau, and Regensburg. In the year 742, continuing the work of organisation begun so well in Bavaria, he succeeded in creating in central Germany the bishoprics of Würzburg, Buraburg, Erfurt, and Eichstädt. To organise the Church and regulate ecclesiastical affairs, he held numerous synods. At the same time, he laboured hard to enforce celibacy, to restore Church property alienated by rulers, and to suppress heresy. In 743, he was made archbishop of Mainz, with jurisdiction over a region from Cologne to Strassburg and from Coire to Worms, and now sought to complete the work of consolidating the German Church. By this time, he had become not only the head of the Church in Germany, but was recognised as a powerful factor in political matters. It is even reported that he crowned Pepin at Soissons (752).[248:1] The great monastery of Fulda was founded (744) and it was destined to become the head of the Benedictine institutions in Germany. Having appointed Lull as his successor at Mainz, he resigned in 754, returned a third time to Frisia as a missionary, and there was slain in 755 as a martyr to the Christian cause. Boniface did more than any other one individual to carry Christianity to the German peoples and to tie the Church of Germany firmly to the papal throne. He was a civiliser and law-giver as well as a Roman missionary.[248:2] After the Apostle Paul he was probably the most eminent in missionary endeavour. His work was continued by his disciple Willibald (b. 700), a relative, a pilgrim to Rome and the Holy Land, and a Benedictine monk, who was made bishop of Eichstädt (741). He called his brother, sister, and others from England as missionaries into Germany. He founded Benedictine monasteries, and it is thought by some that he wrote a biography of his great leader (d. 781). Gregory, an abbot of Utrecht, a Merovingian prince converted by Boniface, worked with his master and took charge of the Frisian mission after his death (755). Sturm, the first abbot of Fulda (710-779),[248:3] a Bavarian nobleman educated by Boniface, had his teacher's bones buried at Fulda and served for years as a missionary among the Saxons (d. 779). Charles the Great gave him support and encouragement.