It is sometimes said that one of the earliest acts of King Alfred in gaining possession of London was to build a fortress or tower within the City. The authority for this statement seems to be nothing more than a passage in the _Chronicle_, under the year 896. “Then on a certain day the king rode up along the river and observed where the river might be obstructed, so that the Danes would be unable to bring up their ships. And they then did thus. They constructed two fortresses on the two sides of the river.” This seems but a slender foundation for the assumption of Freeman that Alfred built a citadel for the defence of London. “The germ of that tower which was to be first the dwelling-place of kings and then the scene of the martyrdom of their victims.” I see no reason at all for the construction of any fortress within the City except the reason which impelled William to build the White Tower, viz. in order to keep a hold over the powerful City. And this reason certainly did not influence Alfred. It is quite possible that Alfred did strengthen the City by the construction of a fortress, though such a building was by no means in accordance with the Saxon practice. It is further quite possible that he built such a tower on the site where William’s tower stood later; but it seems to me almost inconceivable that Alfred, if he wanted to build a tower, should not have reconstructed and repaired the old Roman citadel, of which the foundations were still visible. I confess that I am doubtful about the fortress. What Alfred really did, as I read the _Chronicle_, was to construct two temporary forts near the mouth of the Thames, so as to prevent the Danish ships from getting out. He caught them in a trap.
Let us renew the course of the Danish invasions so far as they concern London. In 893 one army of Danes landed on the eastern shores of Kent and another at the mouth of the Thames. In 894 King Alfred fought them and defeated them, getting back the booty. Some of the Danes took to their ships and sailed round to the west, whither the King pursued them. Others fled to a place near Canvey Island called Bamfleet, where they fortified themselves. Then, for the first time after the Conquest, we find that London is once more powerful, and once more filled with valiant citizens. For the Londoners marched out under Ethelred, Earl of Mercia, their governor, attacked the Danes in their stronghold, took it, put the enemy to flight, and returned to London with all that was within the fort, including the women and the children. In 895 the Danes brought their ships up the Thames and towed them up the Lea to the town of Ware, but the year afterwards the Londoners made their ships useless: whereupon the Danes abandoned them, and the men of London took or destroyed them. Maitland says that “a few years ago”—he writes in 1786—“at the erection of Stanstead Bridge, remains of these ships were found.”