The Britons soon discovered that the Romans had retreated, but made no movement in pursuit. They knew that the legionaries once in open ground were more than their match, and they were well content with the success they had gained. They had lost in all but four hundred men, while they were certain that the Romans had suffered much more heavily, and that there was but little chance of the attack being renewed in the same manner, for if their progress was so slow when they had frost to aid them, what chance would they have when there was scarce a foot of land that could bear their weight? The winter passed, indeed, without any further movement. The Britons suffered to some extent from the damps; but as the whole country was undrained, and for the most part covered with forest, they were accustomed to a damp laden atmosphere, and so supported the fogs of the Fens far better than they would otherwise have done. In the spring, grain, which had been carefully preserved for the purpose, was sown in many places where the land was above the level of the swamps. A number of large boats had been built during the winter, as Beric and Aska were convinced that the next attack would be made by water, having learned from the country people to the west that a vast number of flat bottomed boats had been built by the Romans. Early in the spring fighting again began. A great flotilla of boats descended from Huntingdon, and turning off the side channels entered the swamp. But the Britons were prepared. They were now well provided with tools, and numbers of trees had been felled across the channels, completely blocking the passage. As soon as the boats left the main river, they were assailed with a storm of javelins from the bushes, and the Romans, when they attempted to land, found their movements impeded by the deep swamp in which they often sank up to the waist, while their foes in their swamp pattens traversed them easily, and inflicted heavy losses upon them, driving them back into their boats again. At the points where the channels were obstructed desperate struggles took place. The Romans, from their boats, in vain endeavoured, under the storm of missiles from their invisible foes, to remove the obstacles, and as soon as they landed to attempt to do so they were attacked with such fury that they were forced to fall back.