on Westergo and Oostergo encountered no resistance, since Charles's aim was to bring Poppo to heel. This time no punitive measures were taken against the Frisians. Charles and Poppo's armies met on the banks of the river Boarn, perhaps at Oldeboorne, one of the Frisians' chief commercial centers at the time. The Franks appear to have coveted the trade that passed through there and through Domburg and Dorestad. The Frisians commanded by Poppo used boats to land their army and surprise the Franks. However the Franks had constructed a fortified encampment once on shore and the Frisian army was defeated in the Battle of the Boarn. Poppo was killed in combat and his army was pushed back to Eastergoa. The death of Poppo marked an important phase in the destruction of Frisian paganism. Charles ordered pagan shrines and sanctuaries to be destroyed and carried back to Francia "a great mass of spoils" (magna spolia et praeda). The Franks annexed the Frisian lands between the Vlie and the Lauwers. In 752/753 Boniface wrote a letter to Pope Stephen II, in which it is said that Willibrord destroyed the Frisian pagan sanctuaries and temples. In the Life written by Alcuin are two texts about Willibrord and pagan places of worship. In one he arrived with his companions in Walcheren in the Netherlands where he smashed a sculpture of the ancient religion. In the second text passage Willibord arrived on an island called Fositesland (possibly Heligoland) where a pagan god named Fosite was worshipped. Here he despoiled this god of its sanctity by using the god's sacred well for baptisms and the sacred cattle for food. Emboldened by the success of the Frankish subjugation of Frisia, Boniface returned in 754 to once again attempt to convert the Frisians. He baptized a great number and summoned a general meeting for confirmation at a place not far from Dokkum, between Franeker and Groningen. Instead of the converts he expected, a group of armed inhabitants appeared. The Frisian warriors were angry because he had destroyed their shrines and slew the archbishop, looting his chests and destroying his books. The Frisians consisted of loosely bonded tribes centered on war bands but without great power. In the second half of the 7th century the Frisian kingdom reached its maximum geographic development. After the Frankish conquest In 772, the Frankish king Charlemagne attacked the Frisians east of the Lauwers