This “Venice of the North” lay formerly near the sea, on a gulf of large extent and considerable depth; she was easily accessible, not only to the ordinary run of vessels, but even to the largest of ships. That her port of Damme was large is evident from the fact that in 1213 Philip Augustus, at the head of 1700 sail, closed in it with the allied English and Flemish fleets. This fact alone will give an idea of the importance of Bruges harbour, then one of the largest in Europe. As long as these means of communication with the sea remained open, Bruges maintained her commercial power. The successive accumulations of clay in the Zwyn and in the havens of Damme and Sluys, the outer ports of Bruges, were the causes of the lamentable state of things which followed. About the beginning of the 13th century, vessels sailed into Damme, the port of Bruges, from all quarters of the world, and poured into her markets the trade and wealth of the South and East. Less than a century later the inhabitants of Bruges were compelled to lengthen their maritime channel to Sluys, a small town situated on the Zwyn, about eight miles beyond Damme. The new canal was so constructed as to give access to vessels of from 400 to 500 tons, the largest then built; it passed by Dudzeele and Westcapelle. Hardly had it been opened when the commercial movement of Bruges took a fresh start; from 1420 to 1470 Bruges was the mart of the world, and her fortune had reached its climax. By the Sluys Harbour, into which entered in 1468 with one tide as many as 250 vessels, Bruges was in communication with the North and South of Europe; she was also the only market city for the Netherlands and the Hanseatic League. But from 1470 onwards, i. e. twenty-two years before the discovery of America, the accumulation of clay in the Zwyn again made its disastrous effects felt. Caracks, galleys, and other large vessels could no longer enter the channel. Charles the Bold, in order to deepen it, had the _polder_[80] of the Zwartegat opened, but without avail. Twelve years later, in 1482, matters stood in a much worse condition, and vessels of large draught had completely ceased to appear. No work such as cleansing was carried out, no artificial sluices for such a purpose constructed; and the Sluys Canal, that bold work which during one whole century had maintained the marvellous prosperity of Bruges, now wellnigh useless, became entirely choked up, and like the harbour of Sluys itself, disappeared in the depths of the vast gulf, under the clayey mud and deposits of its alluvia-bearing waves. Bruges was thenceforth condemned to a long decline.