Here the tributaries of the Demer come to an end, but the row of parallel streams is continued by the tributaries of another system, that of the Scheldt. Easternmost of these, and next in order to the Senne, is the Dender, which rises near Leuse and flows past Ath and Alost to the Scheldt at Dendermond. Next comes the Scheldt itself, with the Scarpe and the Haine, its tributaries, which it carries past Tournay and Oudenarde to Ghent, and to the sea at Antwerp. Westernmost of all, the Lys runs past St. Venant, where in Cromwell's time we saw Sir Thomas Morgan and his immortal six thousand, past Menin and Courtrai, and is merged in the Scheldt at Ghent.
The whole extent of the quadrilateral is about one hundred miles long by fifty broad, with a great waterway to the west, a second to the east, and a third, whereof the key is Ghent, roughly speaking midway between them. The earth, fruitful by nature and enriched by art, bears food for man and beast; the waterways provide transport for stores and ammunition. It was a country where men could kill each other without being starved, and hence for centuries the cockpit of Europe.
A glance at any old map of Flanders shows how thickly studded was this country with walled towns of less or greater strength, and explains why a war in Flanders should generally have been a war of sieges. Every one of these little towns, of course, had its garrison; and the manœuvres of contending forces were governed very greatly by the effort, on one side, to release these garrisons for active service in the field, and, on the other, to keep them confined within their walls for as long as possible. Hence it is obvious that an invading army necessarily enjoyed a great advantage, since it menaced the fortresses of the enemy
