[Illustration: CHART TO ILLUSTRATE CÆSAR’S CROSSING THE ENGLISH CHANNEL.]
But inasmuch as the prevailing wind along the English Channel is from the south-west, the reader will observe on consulting a chart that the position of Boulogne for the Gallic traders bound for Dover or the Thames was singularly well placed, inasmuch as it gave the mariner a fair wind outward-bound on most occasions. That fact was doubtless appreciated by Cæsar when he elected to use this port as his starting-place for Britain. He therefore gave orders that his fleet was here to be got in readiness, and then sent forth Volusenus in a galley to reconnoitre the British coast. The ship was a Roman galley manned by oarsmen who had been trained by years of work for the task, and with such a craft as this Volusenus could be independent of wind and accomplish his task with the utmost dispatch. He was away cruising about the English Channel for a period of three days, during which time he had doubtless been able to locate a suitable place where his master’s troops could be disembarked. He had had the opportunity of taking soundings, and--perhaps most important of all to one accustomed almost exclusively to the Mediterranean--of noticing both the range of tide and the force and direction of the strong tidal streams. Similarly, he was able to make a note of the cliffs of Dover and other landmarks. With this knowledge he returned to place himself at Cæsar’s disposal.
On August 25, then, the transports came out from Boulogne. The time was midnight, it wanted five days to full moon, and high water that evening was at 6 p.m., so that the tides were neaps, or at their weakest. We can be quite sure that, acting on the experience of Volusenus in the Channel, it was deliberately intended to avoid spring tides. (It is high water at Boulogne at new and full moon at 11.28.) The transports thus came out of the haven with the last drain of the ebb. But in the offing the tide that night did not make to the eastward till 4 a.m., so there would be the Channel ebb to contend against for some time.
So far all had been splendidly arranged, so that by the time the flood or east-going tide had begun the fleet would all have got clear of the harbour and the oarsmen have been getting into their stride for the passage. Gris Nez and the French cliffs were left behind as the hulls ploughed their way through the heaving sea and sped onwards. But it was not to be a quick passage. The tide, of course, turned against them before they were across, and those transports would not easily be impelled through the waves; but at nine the next morning the oar-propelled galleys which had got ahead during the night approached the cliffs of Dover. Far behind followed the sail-driven transports, so Cæsar let go anchor in Dover Bay, summoned a council of his generals and tribunes, gave them instructions as to the landing-place, told them how to handle both ships and men in disembarking, and then between three and four o’clock that same afternoon the bulky transports wallowed up to join the galleys. Between four and five p.m. the Channel stream off Dover turned to the eastward, and as the wind was favourable Cæsar gave the signal to weigh anchor. Presently the galleys, transports, and the smaller craft were stretched out running past the Foreland with wind and tide to help them. It did not take them long to skirt past St. Margaret’s Bay, and at some point between Walmer and Deal the transports were beached and the journey accomplished. Thus, with careful foresight, Cæsar had got safely across the Channel with his troops and fleet.