But, after all, it is probable that on the religious as well as on the political question the attack came from the Frankish side. It was not so much because the Saxons resented the presence of Christian missionaries among them, as because Charles resented the fact of the Saxons continuing in heathenism, that the Thirty Years’ War of the eighth century was resolved on. Throughout his kingly and imperial career Charles took the religious part of his duties seriously. It was not for nothing that he bore the title of _Christianissimus Rex_, not for nothing that St. Augustine’s famous treatise, _De Civitate Dei_[36] was the favorite companion of his leisure. In his interviews with Pope Hadrian at Rome the reform of the Church’s discipline was apparently the chief subject of conversation; and in the thirty-three Ecclesiastical Councils which were held during his reign he zealously co-operated with the churchmen towards the same end. To such a ruler it was intolerable that tribes which were connected, however loosely, with his kingdom should still profess a belief in the absurdities of heathenism. They must be persuaded, or, if persuasion failed, they must be forced, to become Christians.[37] At an assembly of the Frankish nation held at Worms (July ? 772) Charles announced his purpose of carrying war into the country of the Saxons, and in the early summer he marched with a large army, accompanied by a multitude of bishops, abbots, and presbyters, into the territory of the Angarii, the central tribe. The frontier fortress of Eresburg was taken, and the invaders pressed on to the place where, in the midst of a sacred grove, stood the celebrated Irminsul, a column fashioned to imitate the great world-sustaining ash Yggdrasil, which was the chief object of worship of the Saxon tribes. The idol was hewn down, the temple overthrown, the hoard of gold and silver ornaments deposited there by generations of devout Saxons carried off into Frank-land. The work of destruction lasted three days. It chanced that there was a great scarcity of water in the place where the Irminsul had stood. The army was parched with thirst, and perhaps began to be stirred by superstitious fears that the drought was a punishment for the destruction of the idol. Suddenly, at noonday, while all the army was resting, there was a rush of water along a dry river bed. All the army had enough to drink, and recognized with thanks the Divine approval of their destructive labors. Charles after this marched to the banks of the Weser, held there with the Saxons a great palaver (to borrow a word from modern reports of similar conferences), and received their submission, for what it was worth, accompanied by the surrender of twelve hostages.