The coast-line of England is of curious complexity, and is long out of all proportion to that of any other great European nation, perhaps not even excepting Norway. Consequently its defence presents and always has presented problems of great difficulty. Much of the coast-line is rocky and dangerous even for friendly shipping. In other places, where cliffs are absent, shoals and sand-banks make navigation and landing difficult and dangerous. In looking back to the days when there were no artificial harbours and landing-places, one sees quite clearly that estuaries of rivers would have afforded the safest and most convenient places for landing. That such spots were selected is abundantly proved by tradition, history, and actual contemporary remains. The Danes were quick to seize upon such favourable landing-places. They were provided with boats of great length and slight draught, and their operations were not limited, therefore, to the deeper rivers. During the latter years of the eighth century, and practically throughout the tenth, the Danish raids on Britain were numerous. In due course they established themselves on river-banks, and built permanent camps. According to the "Anglo-Saxon Chronicle," Hasting constructed and occupied a camp at Shoebury for a short period in the year 894. The camp, or such part of it as now exists, has been described by Mr. Spurrell[14] as a Danish work. The place has been much destroyed by the inroads of the sea and the building of various military works, such as barracks, etc., but the plan can be made out, and as restored by Mr. Spurrell, may be described as an irregular quadrangle with rounded corners, and containing an area of about one third part of a square mile. Another Danish camp was constructed the same year at Appledore, the Danes sailing or rowing up the river Rother. According to Somner[15] they discovered at Appledore a half-built fortress, but finding it insufficient for their needs they built a larger entrenchment on the same site. [Illustration: FIG. 18. PLAN OF DANISH CAMP, SHOEBURY, ESSEX] Other places where the Danes settled were Benfleet, probably Swanscombe (although the existing remains of the camp belong probably to the Norman period); Bramber, Sussex; an earthwork surrounding East Mersea Church, Essex; and many other places. Here they constructed their camps and established their forces for long periods, using the adjacent rivers as channels for quickly putting to sea in their swiftly-moving boats when embarking on raiding excursions to the neighbouring coasts. They raided Sheppey in 832, Kent, Canterbury and London in 851. In 876 they took Wareham, where are interesting earthen town-walls, perhaps of Saxon origin. During one or more of their raids in the Medway they penetrated as far as Rochester, which they pillaged. Sandwich and Canterbury suffered much from their visits in the eleventh century.