The Christianization of the country must have been far from complete when the incursions of the Germanic tribes, greatly encouraged by the gradual decline of the Roman Empire, brought a sudden and dramatic change in the life and development of the two Roman provinces. * * * * * [_THE FRANKS_] During the third and fourth centuries, the pressure of the Germanic tribes, which had been considerably delayed by the Roman conquest, reasserted itself. The Rhine frontier was subjected to repeated assaults, which the depleted legions were no longer in a position to repulse effectively. The Franks attacked from the east and the north through Zeeland, while part of the Saxons who attacked Britain raided at the same time the Belgian coast. In spite of the military successes of the Emperors Constantine and Julian, the situation became so threatening that a second line of defences was fortified on the Meuse and along the great Roman highroad running from Tongres to Tournai. In 358, Julian authorized the Franks to settle in the sandy moors east of the Scheldt (Toxandria), and when, at the beginning of the fifth century, Stilicon recalled the legions in order to defend Italy against the Goths, the German tribes, finding themselves unopposed, invaded the country of the Scheldt and the Lys, reducing into serfdom the old inhabitants who had escaped massacre. The Rhine ceased henceforth to be the Empire's frontier. The latter ran now along the great highway from Tongres to Arras. Before their second line of defences the Romans, under AEtius, put up a last fight, but they were defeated by the Frankish king Clodion, who extended his kingdom along the coast as far as the Somme and established himself at Tournai (431), where his grave was discovered twelve centuries later. [_LANGUAGE FRONTIER_]