The Saxons were not far advanced in civilization. The hatred which they entertained against the Germans, who had been converted to Christianity by Boniface[29] and other missionaries, had caused them to break off friendly intercourse with their ancestral associates. They worshipped Odin and other heathen divinities in their forests, as of old. Charlemagne conducted his campaign against them, not so much in the interest of religion as to overthrow the power of a dangerous neighbor, before he went to Italy to subjugate Desiderius. He invaded Saxony and occupied Eresburg, in the vicinity of which was Irminsul, the mystic idol revered by the Saxons.[30] Its significance is still doubtful. Some maintain that it typified the world-ash tree “Ygdrasil,” whose trunk, the Germans believed, was rooted in the underworld and whose branches shadowed Odin’s palace, Walhalla. Others contend that it was a memorial of Arminius who freed Germany from the Roman yoke. The Irminsul was demolished by the Franks. The Saxons at last sued for peace, which Charlemagne granted after they had given him twelve hostages. Then he retired with his army. After this opening success over the Saxons, Charlemagne began his campaign against Desiderius; but hardly had he deposed the Lombardian King before he received the news that the Saxons, in violation of their promise to remain peaceable, had invaded Hesse and were laying it waste. He appeared among them so suddenly and in such force that they were again easily overcome. Once more they submitted, sent him hostages, and were pardoned. It was not his good fortune, however, to enjoy the fruits of victory long. An uprising in Italy, led by Adalgis, son of Desiderius, who had previously escaped, as has been related, next confronted him. Adalgis betook himself to the court of the Greek Emperor to seek his assistance, and made an alliance with his brother-in-law Arighis, Duke of Benevento,[31] who had married the rejected Desiderata. By this alliance he secured the help of the other Italian nobles, who had been left undisturbed upon condition of remaining loyal. The landing of Adalgis with his Greek auxiliaries was the signal for an uprising. Upon receipt of the news of his enemy’s designs from the Pope, Charlemagne hastened to Italy. Only one of the nobles, however, Duke Rotgund in Friaul, had ventured to take up arms, and he was quickly defeated, taken prisoner, and made to do penance the rest of his life. The remaining nobles were stripped of their possessions and the country was divided into earldoms, governed by Frankish nobles.