To render his island retreat more secure, Alfred caused a defensive tower to be erected on each side of the bridge; and, as this was the only point of access by land, he there placed, as sentinels, a few of his most trusty followers, so that they might be ready to give the alarm in the event of their hiding-place being discovered. Scarcely a day passed, but he sallied forth at the head of his little band and assailed the enemy. Too weak to attack the main body, he hung upon, and harassed their foragers; he waylaid the Danish plunderers as they passed on their way to their camp with the spoil, and again wrested from them what they had wrung from his own countrymen. Day and night, Alfred and his followers were ever springing unaware upon the invaders from out the wood, the marsh, and the morass; wherever a clump of trees grew, or a screen of willows gave them shelter, there did the Saxons conceal themselves until the enemy appeared, when, rushing forth, they laid the spoilers low. Such a system of warfare made the king well acquainted with all the secret passes in the neighbourhood, and thus enabled him with his little band to thread his way securely between the bog and the morass, and to attack the Northmen at such unexpected points as they never dreamed it was possible for the enemy to pass. Such a rugged method of attack also inured them to hardships, kindled the martial spirit which had too long slumbered, and thus schooled Alfred in that generalship which he so skilfully brought to bear upon a larger scale when he overthrew the Danes. Even before his rank was discovered, his fame had spread for miles around the country; and all who had spirit enough to throw off the Danish yoke, who preferred a life of freedom in the woods and wilds and had sufficient courage to abandon their homes for the love of liberty, gathered around and fought under the banner of the island stranger. Such of the Saxons as had stooped to acknowledge the Danish rulers, did not escape scathless from the attacks of Alfred and his followers; for he made them feel how feeble was the power upon which their cowardly fears had thrown themselves for protection, when measured beside the strength of their own patriotic countrymen.