Olaf seems to have been sailing in the English Channel when Sweyn died, for as soon as he heard that Ethelred wanted troops to aid him in recovering his kingdom he joined himself to him, hoping, no doubt, to reap some advantage from the war, and to inflict a defeat on the Danes, whose kingdom it was always the desire of the Norsemen to add to the crown of Norway.[34] Together he and Ethelred set sail, steering direct for London, which had always been faithful to its king; but they found the Danish force strongly ensconced behind deep ditches and a high bulwark of stone, timber, and turf in their castle opposite Southwark, which the Danes called Sudvirke or, Southern Town, a great place of trade. King Ethelred sailed up the Thames, and ordered a general assault, but the Danes defended themselves bravely, and Ethelred could make nothing of it. [Illustration: _The Battle of London Bridge_] Between the Danish castle, which afterwards was known as the Tower of London, and Southwark, was old London Bridge, which was broad enough for two wagons to pass each other on it. The Danes had strongly fortified it with barricades and towers, and wooded parapets along the sides, breast-high, and behind this the soldiers, who thickly covered the bridge, stood shooting down upon Ethelred’s fleet of boats beneath them. King Ethelred was very anxious to get possession of the bridge, but it was not clear how this was to be done. Then Olaf the Thick said he would attempt to bring his fleet up alongside the bridge, if the others would do the same. This was his plan. He first ordered his men to land and pull down some old wooden houses that were near the river, and with the wood he made great platforms tied together with hazel withes, so strong that stones would not penetrate them. These he placed over his ships on high pillars so that they stretched out on each side of the boats, and it was possible for his men to fight freely beneath them. The English ships did not take any precautions, but rowed up as they were to the bridge: but so smart a shower of weapons and great stones was shot down upon them that they were forced to retreat, many of them badly damaged and their men wounded; for neither helmet nor shield could hold out against such a storm of missiles. But Olaf’s vessels rowed up quite safely beneath the bridge, where they were sheltered from the enemy above; and when they came under the bridge they tied their cables firmly round the wooden piles upon which the bridge was built, and then rowed off as hard as they could go down-stream, the force of the river and of their oars alike pulling at the piles until they were loosened at the bottom, and dragged out of their place. Now as the bridge was crowded with armed troops, and heavy heaps of stones and weapons were collected upon it, when the piles beneath were loosened it gave way with a great crash, and most of those who were on it fell into the water, the others flying to