VI. Cæsar, penetrating their design, hesitated no longer, in order to terminate the campaign promptly, to advance to the very centre of their strength: he directed his march towards the territory of Cassivellaunus, passing, no doubt, by Maidstone and Westerham. (_See Plate 16._) Arriving at the banks of the Thames, which was then fordable only at one place, perhaps at Sunbury, he perceived a multitude of enemies drawn up on the opposite bank.[405] It was defended by a palisade of sharp pointed stakes, before which other stakes driven into the bed of the river remained hidden under the water. Cæsar was informed of this by prisoners and deserters, and he sent the cavalry forward (probably a certain distance above or below), in order to turn the enemy’s position and occupy his attention, while the infantry destroyed the obstacles and crossed the ford. The soldiers entered the river resolutely, and, although they were in the water up to their shoulders, such was their ardour that the enemy could not sustain the shock, but abandoned the bank and fled. Polyænus relates that on this occasion Cæsar made use of an elephant to facilitate the passage; but, as the “Commentaries” do not mention such a fact, it is difficult to believe.[406] [Sidenote: Submission of a part of Britain.] VII. This check deprived Cassivellaunus of all hope of resistance; he sent away the greatest part of his troops, and only kept with him about 4,000 men, mounted in chariots. (Supposing six _essedarii_ to the chariot, this would still amount to the considerable number of 660 carriages.) Sometimes confining himself to watching the march of the army, at others hiding in places of difficult access, or making a void before the march of the Roman columns; often, also, profiting by his knowledge of the localities, he fell unexpectedly with his chariots on the cavalry when it ventured far plundering and sacking, which obliged the latter to keep near the legions. Thus the damage inflicted on the enemy could not extend beyond the march of the infantry. Meanwhile the Trinobantes, one of the most powerful peoples of Britain, sent deputies to offer their submission and demand Mandubratius for their king. This young man, flying from the anger of Cassivellaunus, who had put his father to death, had come to the continent to implore the protection of Cæsar, and had accompanied him into Britain. The Roman general listened favourably to the demand of the Trinobantes, and exacted from them forty hostages and wheat for the army.