Cæsar, having read the letter, was advised by his friends not to go into Britain upon a bare verbal invitation of the duke, unless he would send such hostages as might be for his security. Without delay, therefore, Androgeus sent his son Scæva with thirty young noblemen nearly related to him. Upon delivery of the hostages, Cæsar, relieved from his suspicion, re-assembled his forces, and with a fair wind arrived at the port of Rutupi. In the meantime Cassibellaun had begun to besiege Trinovantum and ravage the country towns; but finding that Cæsar was arrived, he raised the siege and hastened to meet him. As soon as he entered a valley near Dorobernia,[177] he saw the Roman army preparing their camp: for Androgeus had conducted them to this place, for the convenience of making a sudden assault upon the city. The Romans, seeing the Britons advancing towards them, quickly flew to their arms, and ranged themselves in several bodies. The Britons also put on their arms, and placed themselves in their ranks. But Androgeus with five thousand men lay hid in a wood hard by, to be ready to assist Cæsar, and spring forth on a sudden upon Cassibellaun and his party. Both armies now approached to begin the fight, some with bows and arrows, some with swords, so that much blood was shed on both sides, and the wounded fell down like leaves in autumn. While they were thus engaged, Androgeus sallied forth from the wood, and fell upon the rear of Cassibellaun's army, upon which the hopes of the battle entirely depended. And now, what with the breach which the Romans had made through them just before, what with the furious irruption of their own countrymen, they were no longer able to stand their ground, but were obliged with their broken forces to quit the field. Near the place stood a rocky mountain, on the top of which was a thick hazel wood. Hither Cassibellaun fled with his men after he found himself worsted; and having climbed up to the top of the mountain, bravely defended himself and killed the pursuing enemy. For the Roman forces with those of Androgeus pursued him to disperse his flying troops, and climbing up the mountain after them made many assaults, but all to little purpose; for the rockiness of the mountain and great height of its top was a defence to the Britons, and the advantage of higher ground gave them an opportunity of killing great numbers of the enemy. Cæsar hereupon besieged the mountain that whole night, which had now overtaken them, and shut up all the avenues to it; intending to reduce the king by famine, since he could not do it by force of arms. Such was the wonderful valour of the British nation in those times, that they were able to put the conqueror of the world twice to flight; and being ready to die for the defence of their country and liberty, they, even though defeated, withstood him whom the whole world could not withstand. Hence Lucan in their praise says of Cæsar, "Territa quæsitis ostendit terga Britannis."