While the defeated Celts returned to their chilly homes among the mountains, victorious Caesar resolved to push on at the head of his army toward the Rhine, where some German tribes under a "ferocious headstrong savage" threatened to overrun the country. After marching through utterly unknown country for three days, he heard that fresh swarms of invaders had crossed the Rhine, intending to occupy the more fertile tracts on the French side. They were making for the town we now call Besancon--then, as now, strongly fortified, and nearly surrounded by the river Doubs. By forced marches night and day, Caesar hastened to the town and took it before the arrival of the invaders. Accounts of the German tribes even now approaching were brought in by native traders and Gaulish chiefs, until the Roman soldiers were seized with alarm. Yes, said the traders, these Germans were "men of huge stature, incredible valour, and practised skill in wars; many a time they had themselves come across them, and had not been able to look them in the face or meet the glare of their piercing eyes." The Romans felt they were in an unknown land, about to fight against an unknown foe. Violent panic seized them, "completely paralysing every one's judgment and nerve." Some could not restrain their tears; others shut themselves up in their tents and bemoaned their fate. "All over the camp men were making their wills," until Caesar spoke, and the panic ceased. Seven days' march brought them to the plain of Alsace, some fifty miles from the Rhine. A battle was fought with the German tribes, and "the enemy all turned tail and did not cease their flight until they reached the Rhine." Some swam across, some found boats, many were killed by the Romans in hot pursuit. For the first time Romans beheld the German Rhine--that great river that was to form a barrier for so long between them and the tribes beyond. But Caesar's exploration was not to end here. The following year found him advancing against the Belgae--tribes living between the Rhine and the Seine. In one brilliant campaign he subdued the whole of north-eastern Gaul from the Seine to the Rhine. Leaving Roman soldiers in the newly conquered country, he returned to his province, and was some eight hundred miles away when he heard that a general rebellion was breaking out in that part we now know as Brittany. He at once ordered ships to be built on the Loire, "which flows into the ocean," oarsmen to be trained, seamen and pilots assembled.