Caswallon, unshaken, fell back on his guerrilla tactics. His chariotry and cavalry were intact. Cæsar says that they were about four thousand, a moderate estimate which shows it to be near the truth. With them he faced his great antagonist, while the southern levies took refuge in the Weald, and those of the Catuvellauni went back to entrench the fords of the Thames. From the neighbourhood of Canterbury to that of London the Romans advanced slowly, probably along the line of the later Watling Street, while Caswallon moved parallel to them in the woods, hung about the line of march, and harassed it incessantly. The Gallic horsemen never dared to move far from the infantry columns. Caswallon was ever watchful. But it was not guerrilla warfare, however skilful and gallant, that could stay the march of Cæsar’s legions. The advance was slow and difficult, but still it continued steadily until the Thames was reached. Caswallon retreated across it, and the Romans followed.
Where the British leader was stationed it is hard to say. The course of the Thames, meandering among marshes, must have varied much from what it is to-day, and, having no embankments, it was probably much shallower. Cæsar may have crossed near Brentford or Halliford; there are said to be the remains of a stockade in the bed of the river opposite the former place. At any rate, Cæsar gives the impression that the ford was well known. Its northern end was guarded by entrenchments, and the passage itself was obstructed by stakes. The position was a formidable one, yet it was carried with unexpected ease. The Roman cavalry led the way into the Thames, the infantry followed, with the water at their necks, passed the stakes—how we do not know—carried the stockade, and drove the Britons off towards the north.
CÆSAR’S TWO EXPEDITIONS TO BRITAIN IN 55 AND 54 B.C.
The probable line of advance on Verulam is indicated by the broken line.
Cæsar, having passed the Thames, halted for a time to receive hostages and supplies from the neighbouring Trinobantes. Caswallon fell back on his tribal stronghold (almost certainly Verulam), and sent orders to the four sub-kings of Kent to attack Cæsar’s base-camp, and so draw him back from the Thames. It was the last fine stroke of Caswallon’s admirable strategy, but fate was against him. Atrius marched boldly out to attack the men of Kent, defeated and scattered them with great loss, capturing a prominent chief named Lugotorix. Cæsar, having rested his men in the Trinobantian territory near London, advanced upon Verulam. He describes it as a great earthwork among woods and marshes. It was captured by a simultaneous attack on two fronts. The British loss was heavy, and included thousands of captives, besides vast quantities of supplies. Verulam had evidently been the place of refuge of a great part of the tribe.
Caswallon had done his best and had failed. Through Commius, who was with the Romans, he made overtures, and Cæsar was not unready to accept them. Reports were coming in from Labienus of alarming unrest among the Gauls, which was soon to blaze out into a great national uprising. It was clearly time to go. Cæsar was justified in supposing that he had done enough to convince the Britons that interference in Gallic affairs would, for the future, be dangerous. His terms of peace were, therefore, moderate enough. Caswallon was to keep the peace with Mandubracius, pay a yearly tribute to Rome, and, of course, give hostages for the observance of the conditions. They were accepted, and, with his hostages and captives, Cæsar returned to the coast. Two trips were necessary owing to the large number of prisoners to be transported. Apart from them (and being only fit for rough field and house work, they would hardly fetch a high price) there appears to have been little spoil of value, much to the disappointment of many greedy officers. Cicero quaintly voices this discontent in his letters. We hear, however, that Cæsar dedicated to Venus a cuirass ornamented with British pearls, so that possibly some were lucky.
All this probably weighed little with Cæsar beside the fact that he was not likely to have Britain on his rear during the Gallic disturbances. If Caswallon, a man, as far as we can see, of remarkable ability for war, had been able to intervene in the great struggle with Vercingetorix two years later, the consequences might have been very serious. As it was, we hear no more of British aid given to the Gauls, and Cæsar was content. Whether the tribute was paid we do not know; possibly it was so long as Cæsar was in Gaul. When the civil war broke out, it probably lapsed; but the general political results of the expedition appear from Cæsar’s point of view to have been satisfactory.