Besides the ports on the Mediterranean, or on the rivers which flow into that sea, the Gauls in Cæsar's time, or shortly afterwards, seem to have had several, ports on the ocean. Cæsar reckons the present Nantz, though at some distance from the sea, as inhabited by people who were skilled in maritime affairs; and he expressly informs us, that he built his ships at a port at the mouth of the Seine, when he was preparing to invade Britain. In his wars against the Vanni he brought ships from the present provinces of Saintoinge and Poitou, which we may thence conclude were inhabited by people skilled in maritime affairs. In later times, there was a marsh filled with sea-water, not far from Bourdeaux, which made that city a convenient port, and a place of considerable commerce. Strabo mentions a town of some commerce, situated on the Loire, which he represents as equal in size to Narbonne and Marseilles; but what town that was has not been ascertained.
The most powerful and commercial, however, of all the tribes of Gaul, that inhabited the coasts near the ocean, in the time of Cæsar, were the Vanni. These people carried on an extensive and lucrative trade with Britain, which was interrupted by the success of Cæsar, (who obliged them, as well as the other tribes of Gaul, to give him hostages,) and which they apprehended was likely to be still further injured by his threatened invasion of Britain; in order to prevent this, as well as to liberate themselves, they revolted against the Romans. As Cæsar was sensible that it would be imprudent and unsafe to attempt the invasion of Britain, so long as the Vanni were unsubdued and powerful at sea, he directed his thoughts and his endeavours to build and equip such a fleet as would enable him successfully to cope with them on their own element. In building his ships, he followed the model of those of his enemies, which were large, flat-bottomed, and high in the head and stern: they were strong-built, and had leathern sails, and anchors with iron chains. They had a numerous squadron of such vessels, which they employed chiefly in their trade with Britain: they seem also to have derived considerable revenue from the tribute which they levied on all who navigated the adjacent seas, and to have possessed many ports on the coast. Besides their own fleet, the Britons, who were their allies, sent ships to their assistance; so that their united force amounted to 220 sail, well equipped, and manned by bold and expert seamen.
To oppose this formidable fleet, Caesar ordered ships to be built on the Loire, and the rivers running into it, exactly, as we have just stated, after the model of the ships of the Vanni; for he was informed, or learnt by experience, that the vessels which were used in the Mediterranean were not fit for navigating and fighting on the ocean, but that such as were employed on the latter must be built, not only stronger, but flat-bottomed, and high at the head and stern, in order to withstand the fury of the waves and winds, which was greater in the ocean than in the Mediterranean, and at the same time to sail up the rivers, or in very shallow water, and to take the ground, without injury or danger. Not being able, however, to build in time a sufficient number of ships in Gaul, after the model of those of the Vanni, he was under the necessity of bringing some from the south coast of Gaul, and other parts of the Mediterranean Sea; he also collected all the experienced pilots he could meet with, who were acquainted with the coasts, and with the management of such ships, and exercised a sufficient number of men at the oar, to navigate them.
These preparations were all indispensably requisite; for in the battle which ensued, the Vanni and their allies fought their ships with a skill and a valour of which the Romans had not had any previous example; and they would certainly have been beaten, if they had not, by means of sharp engines, cut the ropes and sails of the hostile fleet, and thus rendered their ships unmanageable: in this state they were easily and speedily captured. As the Vanni had on this occasion mustered all their forces, their defeat put an end to their resistance, and removed Caesar's principal obstacle to the invasion of Britain.
The motives which induced Caesar to invade Britain can only be conjectured, if, indeed, any other motive operated on his mind besides ambition, and the love of conquest and glory; stimulated by the hope of subduing a country, which seemed the limit of the world to the west, and which was in a great measure unknown. He was, probably, also incited by his desire to punish the Britons for having assisted the Vanni; and Suetonius adds, that he was desirous of enriching himself with British pearls, which were at that time in high repute.
Before he undertook this expedition, which, even to Caesar, appeared formidable, he resolved to learn all he could respecting Britain. For this purpose, he collected the merchants who traded thither from all parts of Gaul; but they could afford him no satisfactory information. They had visited only the opposite coast of Britain; of the other parts of the country, of its extent, its inhabitants, &c., they were utterly ignorant. Under these circumstances, therefore, he sent one of his officers in a galley, who, after being absent five days, during which however he had not ventured to land, returned to Caesar, and acquainted him with the little he had observed.
Caesar resolved to invade Britain immediately: for this purpose, he ordered eighty transports to take on board two legions; and the cavalry to be embarked in eighteen more, at a port a few miles off. The enterprize was attended with considerable difficulty, from the opposition of the Britons, and the large ships of the Romans not being able to approach very near the land. It was however successful, and the Britons sued for and obtained peace.
This they were soon induced to break, in consequence of Caesar's fleet being greatly injured by a storm; and the violence of the wind raising the tide very high, the Roman sailors, unaccustomed to any tides except the very trifling ones of the Mediterranean, were still more alarmed and dispirited. The Britons, after attacking one of the legions, ventured on a still bolder enterprize, for they endeavoured to force the Roman camp: in this attempt they were defeated, and again obliged to sue for peace. This was granted, and Caesar returned to Gaul. But the Britons not fulfilling the conditions of the peace, Caesar again invaded their country with 600 ships and twenty-eight galleys; he landed without opposition, and defeated the Britons. His fleet again encountered a storm, in which forty ships were lost, and the rest greatly damaged. In order to prevent a similar accident, he drew all his ships ashore, and enclosed them within the fortifications of the camp. After this, he had no further naval operations with the Britons.
It will now be proper to consider the state of Britain at the period of its invasion by the Romans, with respect to its navigation and commerce. It is the generally received opinion, that the Britons, at the time of the invasion of their island by Caesar, had no ships except those which he and other ancient authors, particularly Solinus and Lucan, describe. These were made of light and pliant wood, their ribs seem to have been formed of hurdles, and they were lined as well as covered (so far as they were at all decked) with leather. They had, indeed, masts and sails; the latter and the ropes were also made of leather; the sails could not be furled, but, when necessary, were bound to the mast. They were generally, however, worked with oars, the rowers singing to the stroke of their oars, sometimes accompanied by musical instruments. These rude vessels seem not to have been the only ones the Britons possessed, but were employed solely for the purpose of sailing to the opposite coasts of Gaul and of Ireland. They were, indeed, better able to withstand the violence of the winds and waves than might be supposed from the materials of which they were built. Pliny expressly states that they made voyages of six days in them; and in the life of St Columba, (in whose time they were still used, the sixth century,) we are informed of a vessel lined with leather, which went with oars and sails, sailing for fourteen days in a violent storm in safety, and gaining her port. The passage therefore in these boats across the Irish Channel, could not be so very dangerous as it is represented by Solinus.
But notwithstanding the authority of Caesar, Pliny, Solinus, and Lucan, who mention only these leathern vessels, and that the poet Avienus, who lived in the fourth century, expressly states, that even in his time the Britons had no ships made of timber, but only boats covered with leather or hides; there are circumstances which must convince us that they did possess larger, stronger, and more powerful ships. Caesar informs us, that the Britons often assisted the Gauls, both by land and sea; and we have seen that they sent assistance to the Vanni, in their sea-fight against Caesar; but it is not to be supposed that their leathern boats, small and weak as they were, could have been of any material advantage in an engagement with the Roman ships. Besides, the Britons, who inhabited the coast opposite to Gaul, carried on, as we have remarked, a considerable and regular trade with the Vanni; it is, therefore, reasonable to presume, that they would learn from this tribe, the art of building ships like theirs, which were so well fitted for these seas, as well as for war, that Caesar built vessels after their model, when he formed the determination of opposing them by sea.