Having thus vindicated the Roman claim to the frontiers of Gaul against other invaders, the proconsul devoted his second summer to the subjugation of the Belgæ, the most warlike and the most remote of the Gauls. The second book tells how this was accomplished. There was one moment when the conqueror's career came near ending prematurely. One of the Belgian tribes, the valiant Nervii, surprised and nearly defeated the Roman army. But steady discipline and the dauntless courage of the commander, never so great as in moments of mortal peril, saved the day, and the Nervii are immortalized as the people who nearly destroyed Cæsar. These unprecedented successes all round the eastern and northern frontiers thoroughly established Roman prestige and strengthened Rome's supremacy over the central Gauls, who were already her allies, at least in name. But much yet remained to do. The work was but fairly begun. The third book tells of the conquest of the western tribes. The most interesting episode is the creation of a fleet and the naval victory over the Veneti on the far-away coast of Brittany. In the fourth year Cæsar crossed the Rhine, after building a wonderful wooden bridge in ten days, carried fire and sword among the Germans on the further bank, and returned to his side of the river, destroying the bridge behind him. Modern schoolboys wish he had never built it. Later in the season he made an expedition into Britain. This was followed in the fifth year by an invasion of the island in greater force. To people of our race this portion of the Commentaries is especially interesting. The southern part of the country was overrun, the Thames was crossed some miles above London, and several victories were gained, but no organized conquest was attempted. That remained for the age of Claudius and later emperors.