The strife with the Danes in the Thames valley raged from before the time of Alfred's birth. Stow and others have supposed that London was wrecked in 839, and lay waste until Alfred restored it; but it has been shown that the first attack on the city must have been in 842.[24] In 851 a great host of the pagans came with 350 ships to the mouth of the river Thames, and sacked Canterbury "and also the city of London, which lies on the confines of Essex and Middlesex, but the city belongs of right to Essex."[25] Before this time London had become subject to the overlordship of Mercia, and Behrtwulf the Mercian was killed in its defence. There is a charter of Burgred, king of Mercia, relating to London, 857; in 872-74 the city was taken by Halfdan the Dane, and Burgred, king of Mercia, was ejected from his kingdom. In the coin room of the British Museum there is a remarkable coin which bears the legend ALFDENE RX[Maltese Cross], and on the reverse the monogram of London which was later used by Alfred on his coins (Fig. 14). The obverse bears the same type as that used on the coins of Ceolwulf, whom Halfdan set up as his creature in Mercia: it cannot be doubted that Halfdan's coin was struck as a memorial of his wintering in London in 872-73, as described in the Anglo-Saxon Chronicle. All now was confusion, "down and up, and up and down, and dreadful," till at the peace of Wedmore, in 878, Alfred made a division of the country with the Danish leader Guthrum, by a boundary defined in the agreement as "upon the Thames along the Lea to its source, then right to Bedford and upon the Ouse to Watling Street." London thus fell to Alfred, who repaired it in 886 and made it again habitable, and gave it into the hands of his son-in-law Ethered.[26] Ethered was Ealdorman of Mercia, so London was still practically the Mercian capital, and remained so till the death of Ethered. London all the time was the chief city in the kingdom, but it then had to enter into competition with Winchester, the local capital of the dominating kingdom. [Illustration: FIG. 14.--COIN OF HALFDAN WITH MONOGRAM OF LONDON.] In 893 there was a fresh attack by the Danes, but they were defeated outside the city by the men of London, led by Ethered. In the account of this raid from the south coast through Farnham and northwards across the Thames, as given in Ethelweard's Chronicle, the Danes are said to have been besieged on Thorney Isle (_Thornige Insula_), the site of the abbey of Westminster. The Danes then passed eastward and took up positions at Mersea, Shoebury, and probably Welbury, near the Lea, in all of which places there are traces of earthworks.[27] [Illustration: FIG. 15.--SAXON SWORDHILT.]