Caesar did not wait for them to move. He advanced at once to Rheims, where he called the Senate together and encouraged them to be constant to the Roman alliance. He sent a party of Aedui down the Seine to harass the territory of the Bellovaci and recall them to their own defence; and he went on himself to the Aisne, which he crossed by a bridge already existing at Berry-au-Bac. There, with the bridge and river at his back, he formed an entrenched camp of extraordinary strength, with a wall 12 feet high and a fosse 22 feet deep. Against an attack with modern artillery such defences would, of course, be idle. As the art of war then stood, they were impregnable. In this position Caesar waited, leaving six cohorts on the left bank to guard the other end of the bridge. The Belgae came forward and encamped in his front. Their watch-fires at night were seen stretching along a line eight miles wide. Caesar, after feeling his way with his cavalry, found a rounded ridge projecting like a promontory into the plain where the Belgian host was lying. On this he advanced his legions, protecting his flanks with continuous trenches and earthworks, on which were placed heavy cross-bows, the ancient predecessors of cannon. Between these lines, if he attacked the enemy and failed, he had a secure retreat. A marsh lay between the armies; and each waited for the other to cross. The Belgians, impatient of delay, flung themselves suddenly on one side and began to pour across the river, intending to destroy the cohorts on the other bank, to cut the bridge, and burn and plunder among the Remi. Caesar calmly sent back his cavalry and his archers and slingers. They caught the enemy in the water or struggling out of it in confusion; all who had got over were killed; multitudes were slaughtered in the river; others, trying to cross on the bodies of their comrades, were driven back. The confederates, shattered at a single defeat, broke up like an exploded shell. Their provisions had run short. They melted away and dispersed to their homes, Labienus pursuing and cutting down all that he could overtake. The Roman loss was insignificant in this battle. The most remarkable feature in Caesar's campaigns, and that which indicates most clearly his greatness as a commander, was the smallness of the number of men that he ever lost, either by the sword or by wear and tear. No general was ever so careful of his soldiers' lives. Soissons, a fortified Belgian town, surrendered the next day. From Soissons Caesar marched on Breteuil and thence on Amiens, which surrendered also. The Bellovaci sent in their submission, the leaders of the war party having fled to Britain. Caesar treated them all with scrupulous forbearance, demanding nothing but hostages for their future good behavior. His intention at this time was apparently not to annex any of these tribes to Rome, but to settle the country in a quasi-independence under an Aeduan hegemony.