The Popes needed to quickly reinvent their relationship to secular authority. Even though the neighboring Lombard kings were no longer heretical, they were often hostile. The more powerful and more distant Franks, which had by and large been allies of the Empire, were an alternative option as potential protectors. In 739, Gregory III sent a first embassy to Charles Martel seeking protection against Liutprand, King of the Lombards, but the Frankish strongman had been Liutbrand's ally in the past and had asked him in 737 to ceremonially adopt his son. The Papacy had more luck with the latter, Pepin the Short, who succeeded Charles in October 741 together with his elder brother Carloman (who withdrew from public life and became a monk in 747). Pope Zachary was pressed into action by the final Lombard campaign against the exarchate of Ravenna, whose fall in mid-751 sealed the end of Byzantine rule in Central Italy. He was in contact with the Frankish ruling elites through the venerable Boniface, Archbishop of Mainz, and other clerics such as Burchard of Würzburg and Fulrad. In March 751 he moved to depose Childeric III, the last Merovingian King, following which Pepin was dedicated as King of France in Soissons. In 754, Zachary's successor Pope Stephen II undertook the first-ever papal visit north of the Alps, met Pepin in Ponthion and anointed him as king at Saint-Denis on July 28, setting the template for later rites of coronation of French Kings. Stephen further legitimized the Carolingian dynasty by also anointing Pepin's sons Charles and Carloman, by prohibiting the election of any non-descendant of Pepin as king, and by proclaiming that "the Frankish nation is above all nations". This in return prompted the Donation of Pepin in 756, cementing the Popes' rule over the Papal States over the next eleven centuries. Subsequently in 773-774, Pepin's son and successor Charlemagne conquered the Lombard Kingdom of Italy.