On his arrival in Spain, he promptly raised ten new cohorts, which, joined to the twenty others already in the country, furnished him with three legions, a force sufficient for the speedy pacification of the province.[1056] Its tranquillity was incessantly disturbed by the depredations of the inhabitants of Mount Herminium,[1057] who ravaged the plain. He required them to establish themselves there, but they refused. Cæsar then began a rough mountain war, and succeeded in reducing them to submission. Terrified by this example, and dreading a similar fate, the neighbouring tribes conveyed their families and their most precious effects across the River Durius (_Douro_). The Roman general hastened to profit by the opportunity, penetrated into the valley of the Mondego to take possession of the abandoned towns, and went in pursuit of the fugitives. The latter, on the point of being overtaken, turned, and resolved to accept battle, driving their flocks and herds before them, in the hope that, through this stratagem, the Romans would leave their ranks in their eagerness to secure the booty, and so be more easily overcome. But Cæsar was not the man to be caught in this clumsy trap; he left the cattle, went straight at the enemy, and routed them. Whilst occupied in the campaign in the north of Lusitania, he learnt that in his rear the inhabitants of Mount Herminium had revolted again with the design of closing the road by which he had come. He then took another; but they made a further attempt to intercept his passage by occupying the country between the Serra Albardos[1058] and the sea. Defeated, and their retreat cut off, they were forced to fly in the direction of the ocean, and took refuge in an island now called _Peniche de Cima_, which, being no longer entirely separated from the continent, has become a peninsula. It is situated about twenty-five leagues from Lisbon.[1059] As Cæsar had no ships, he ordered rafts to be constructed, on which some troops crossed. The rest thought that they might venture through some shallows, which, at low tide, formed a ford; but, desperately attacked by the enemy, they were, as they retreated, engulphed by the rising tide. Publius Scævius, their chief, was the only man who escaped, and he, notwithstanding his wounds, succeeded in reaching the mainland by swimming. Subsequently, Cæsar obtained some ships from Cadiz, crossed over to the island with his army, and defeated the barbarians. Thence he sailed in the direction of Brigantium (now _La Corogne_), the inhabitants of which, terrified at the sight of the vessels, which were strange to them, surrendered voluntarily.[1060] The whole of Lusitania became tributary to Rome.