In the following spring, however, Cæsar again returned to Britain. This time, instead of eighty vessels his fleet consisted of eight hundred, while his army numbered many thousands. The Britons had again gathered in great strength to repel the invaders, but when they saw so many ships they grew afraid and fled to their forests. So Cæsar landed without difficulty at Romney marsh. At length, led by a brave chief, called Cassivellaunus, the tribes determined to try to drive the Romans from their shore. Cassivellaunus did not conquer the Romans, but he proved a brave and skilful commander, and constantly harassed them. At last, however, his capital was taken, and he then sent messengers to treat with Cæsar. Cæsar received the envoys and demanded from them hostages, and the promise that their tribes would pay a yearly tribute to Rome. Then in September 54 B.C., when his fleet, which had been damaged by a storm, was repaired, he again went back to Gaul. Here he was greeted with the sad news that his daughter Julia was dead. Julia had often smoothed away the jealousies of her husband, the irritations of her father, and both Pompey and Cæsar mourned for her loss. Their friends also were troubled. They foresaw that now the beautiful Julia was no longer alive, it would not be long before the two great generals quarrelled. And that was a grave thought. For the peace of Rome depended on the friendship of Pompey and Cæsar. Cæsar’s work in Gaul was not yet finished. In 52 B.C. the tribes in the south made one more desperate stand against the power of Rome, which seemed to be pressing more and more heavily upon them. The rebellion was led by a young chief named Vercingetorix, who had seized the town of Gergovia, the capital of his tribe and his own birthplace. Cæsar, when he heard that Gergovia was in the hands of the barbarians, hastened to the town and at once laid siege to it. But to his surprise the town withstood every effort he made to take it. For the first time Cæsar was unable to capture a Gallic town, and not only so, but he was forced to raise the siege. When Vercingetorix saw the Romans retreating, he believed that now was the time to attack them, and he led his followers against the foe. But on the battlefield the Gauls were no match for the legions of Rome, and Vercingetorix was forced to flee from the field with only a remnant of his army. The young Gaul succeeded in reaching the town of Alesia, which he at once began to fortify. Cæsar speedily followed the enemy to Alesia, and when he saw the Gauls within the walls of the town, he determined to keep them there. He at once ordered his men to set to work to dig trenches, and to build forts round the walls, that no one might escape. But one night, when it was dark, the young Gaul sent messengers to summon the neighbouring tribes to come to his aid.