Commentaries on the Gallic War
By Julius Caesar
4.20. During the short part of summer which remained, though in these countries the winters are early - as all Gaul lies toward the north - Caesar nevertheless resolved to proceed into Britain, because he discovered that in almost all the wars with the Gauls, help had been furnished to our enemy from that country; and even if the time of year should be insufficient for carrying on the war, yet he thought it would be of great service to him if he only entered the island, and investigated the character of the people, and got knowledge of their localities, harbors, and landing-places, all which were for the most part unknown to the Gauls. For neither does anyone except merchants generally go there, nor even to them was any portion of it known, except the sea-coast and those parts which are opposite to Gaul. Therefore, after he had summoned to him the merchants from all parts, he could learn neither what was the size of the island, nor what or how numerous were the nations which inhabited it, nor what system of war they followed, nor what customs they used, nor what harbors were convenient for a great number of large ships. . . .
4.33. Their [Britons'] mode of fighting with their chariots is this: firstly, they drive about in all directions and throw their weapons and generally break the ranks of the enemy with the very dread of their horses and the noise of their wheels; and when they have worked themselves in between the troops of horse, leap from their chariots and engage on foot. The charioteers in the mean time withdraw some little distance from the battle, and so place themselves with the chariots that, if their masters are overpowered by the number of the enemy, they may have a ready retreat to their own troops. Thus they display in battle the speed of horse, [together with] the firmness of infantry. . . .
5.11. When he [Caesar] had come there, greater forces of the Britons had already assembled at that place, the chief command and management of the war having been entrusted to Cassivellaunus, whose territories a river, which is called the Thames, separates from the maritime states at about eighty miles from the sea. At an earlier period perpetual wars had taken place between him and the other states; but, greatly alarmed by our arrival, the Britons had placed him over the whole war and the conduct of it.
5.12. The interior portion of Britain is inhabited by those of whom tradition records that they were born in the island itself; the maritime portion by those who came over from the country of the Belgae for the purpose of plunder and making war; almost all of whom are called by the names of those states from which they migrated to Britain, where, having waged war, they continued to live, and began to cultivate the lands. The number of the people is countless, and their buildings exceedingly numerous, for the most part very like those of the Gauls; the number of cattle is great. They use either brass or iron rings, determined at a certain weight, as their money. Tin is produced in the midland regions; in the maritime, iron; but the quantity of it is small: they employ brass, which is imported. There, as in Gaul, is timber of every description, except beech and fir. They do not regard it as lawful to eat the hare, and the cock, and the goose; they, however, breed them for amusement and pleasure. The climate is more temperate than in Gaul, the colds being less severe. . . .
5.14. The most civilized of all these nations are those who inhabit Kent, which is entirely a maritime district, nor do they differ much from the Gallic customs. Most of the inland inhabitants do not sow corn, but live on milk and flesh, and are clad with skins. All the Britons, indeed, dye themselves with woad, which occasions a bluish color, and thereby have a more terrible appearance in battle.
They wear their hair long, and have every part of their body shaved except their head and upper lip. Ten and even twelve have wives common to them, and particularly brothers share wives with brothers, and fathers with their sons; but if there are any children by these wives, they are reputed to be the offspring of the man whom the mother first married when she was a virgin.
Source: Marquette University Ancient History and Archaeology Book 4 of Gallic Wars and Book 5 of the Gallic Wars [https://faculty.history.wisc. edu/sommerville/123/123%20week1.HTM]