On this the wall was built. It was faced on both sides with square stones, the space between filled up with rubble and cement, the total thickness being 4 feet. The height of the wall was 8 feet, and at intervals of 30 yards apart towers were raised 10 feet above it, one of these being placed at either side of the entrance. Here the bank was cut away, and solid buttresses of masonry supported the high gates. The opening in the outer bank was not opposite to the gate in the inner, being fifty yards away, so that any who entered by it would have for that distance to follow the ditch between the two banks, exposed to the missiles of those on the wall before arriving at the inner gate. Five hundred men laboured incessantly at the work. The stone for the walls was fortunately found close at hand, but, notwithstanding this, the work took nearly six months to execute; deep wells were sunk in the centre of the fort, and by this means an ample supply of water was secured, however large might be the number within it. A very short time after the commencement of the work the news arrived that King Edmund of East Anglia had gathered his forces together and had met the Danes in a great battle near Thetford on Sunday the 20th of November, and had been totally defeated by them, Edmund himself having been taken prisoner. The captive king, after having been for a long time cruelly tortured by the Danes, was shot to death with arrows. It was not long after this that news came that the whole of East Anglia had fallen into the hands of the Danes. Early in the month of February, 871, just as the walls of his fort had begun to rise, a messenger arrived from the king bidding Edmund assemble all the men in his earlship and march at once to join him near Devizes, as the news had come that a great Danish fleet had sailed up the Thames and had already captured the royal town of Reading. Messengers were sent out in all directions, and early the next morning, 400 men having assembled, Edmund and his kinsman marched away with them towards Devizes. Upon their arrival at that town they found the king and his brother with 8000 men, and the following day the army moved east towards Reading. They had not marched many miles before a messenger arrived saying that two of the Danish jarls with a great following had gone out to plunder the country, that they had been encountered by Aethelwulf, Earl of Berkshire, with his men at Englefield, and a fierce battle had taken place. The Saxons had gained the victory, and great numbers of the Danes had been slain, Sidroc, one of their jarls, being among the fallen.