The Franks alone of all the barbarians who swept over Europe at the time of the decay of the Western Empire, were Catholic from their first conversion to Christianity; and to this circumstance the French kings owed their title of Eldest Sons of the Church. It was by the influence of a French princess, Bertha, the Christian wife of Ethelbert, king of Kent, that St. Augustine and his companions were favourably received in England; whilst another princess of the same race, Ingunda, who married the son of the Visigoth king of Spain, is said to have brought about the conversion of her husband from Arianism to the Catholic faith, by her own constancy under persecution. [Sidenote: The Church under Charlemagne.] During the reign of the Emperor Charlemagne (A.D. 768-A.D. 814), the French monasteries became seats of learning, and amongst the learned men who assisted the Emperor in his efforts for the religious and intellectual improvement of his people, may be mentioned the English Alcuin, who held an honourable position at the French court as the instructor and adviser of the monarch and his sons. [Sidenote: The French Liturgy.] The Gallican Liturgy, a branch of the Primitive Liturgy of Ephesus, was entirely disused by order of Charlemagne, and the Roman service used in its stead. [Sidenote: Conversion of the Northmen.] From about A.D. 870 the Northmen, who had long been a scourge to France, began to settle down in that country, and were gradually converted to the Christian Faith, their chief, Rollo, marrying a Christian princess, A.D. 911, and being baptized in the following year. [Sidenote: The Crusades.] A French {125} hermit, Peter of Auvergne, was the instigator of the First Crusade, which was preached by him at Clermont, and joined by a large number of French nobles, the command of the expedition being given to Godfrey de Bouillon, Duke of Lorraine. The system of Crusades thus inaugurated for the defence of Christian pilgrims in the Holy Land, and the winning back of the Holy Places from the hands of the Mahometans, was turned to a cruel and unjustifiable use in the thirteenth century, when Innocent III. proclaimed a Crusade against the Albigenses in the South of France, in which multitudes of these unhappy and misguided men were slaughtered. [Sidenote: Rupture between France and the Pope.]