Soon after, in a sortie that was made from the city, one of the Roman deputies joined the soldiers, and killed a Gaulish champion of great size and stature. On this being reported to Brennus he sent messengers to Rome, demanding that the man who had slain one of his chiefs, when no war existed between the Gauls and Romans, should be delivered into his hands for punishment. The senate voted to do so, as the demand seemed reasonable; but an appeal was made to the people, and they declared that the culprit should not be given up. On this answer being taken to Brennus, he at once ordered that the siege of Clusium should be abandoned, and marched with his whole army upon Rome. A Roman army, forty thousand strong, was hastily raised, and crossed the Tiber, marching towards Veii, where they expected to meet the advancing enemy. But they reckoned wrongly: the Gauls came down the left bank of the river, plundering and burning as they marched. This threw the Romans into the greatest alarm. For many miles above Rome the Tiber could not be forded, there were no bridges, and boats could not be had to convey so large an army. The Romans were forced to march back with all speed to the city, cross the river there, and hasten to meet their foes before they got too near at hand. But when they came within sight of the Gauls the latter were already within twelve miles of Rome. The Roman army was drawn up behind the Alia, a little stream whose deep bed formed a line of defence. But the Gauls made their attack upon the weakest section of the Roman army, hewing them down with their great broadswords, and assailing their ears with frightful yells. The Roman right wing, formed of new recruits, gave way before this vigorous charge, and in its flight threw the regular legions of the left wing into disorder. The Gauls pursued so fiercely that in a short time the whole army was in total rout, and flying as Roman army had never fled before. Many plunged into the river, in hope of escaping by swimming across it. But of these the Gauls slew multitudes on the banks, and killed most of those in the stream with their javelins. Others took refuge in a dense wood near the road, where they lay hidden till nightfall. The remainder fled back to the city, where they brought the frightful tidings of the utter ruin of the Roman army. The news threw Rome into a panic. Of those who escaped from the battle, the majority had crossed the river and made their way to Veii. No other army could be raised. Most of the other inhabitants left the city, as the people of Athens had done when the army of Xerxes approached. It was resolved to abandon the city to the barbarians, but to maintain the citadel, the home of the gods of Rome. The holy articles in the temples were buried or removed, the Vestal Virgins sent away, and the flower of the patricians took refuge in the Capitol, determined to defend to the last that abiding-place of the guardian gods of Rome.