The field of operations for the Duke's army may be described roughly as a quadrilateral, of which the sea forms the northern side, the canal from Dunkirk to Bergues the west, the canal from Bergues to Furnes the south, and a line drawn from Furnes to the sea the east. From east to west the ground thus enclosed was divided roughly into two parallel strips; the northern half consisting of the sandhills known as the Dunes, together with a narrow plain of level sandy ground within them; and the southern half of a huge morass called the Great Moor, which consisted partly of standing water, partly of swamp, but was all open to inundation by admitting the tidal water from the sluices of Dunkirk. Tetteghem, which formed the left of the Duke's position, rested upon this swamp, and commanded the only road that led across it to the White House, and so to Freytag's army. The position itself was in many respects disadvantageous. It was much broken up by innumerable little ditches, hedges, and patches of brushwood, all of which the troops had to clear away with their side-arms for want of better tools; it was wholly destitute of drinking water, that in the canals being brackish, and that found in the wells unpalatable; and, finally, it lay open to the minutest inspection from the tower of Dunkirk Cathedral. But this was not the worst. The Duke had looked for a fleet to cover his right flank, which had suffered from the enemy's gunboats during the march upon Ghyvelde, and for transports bringing heavy artillery and other materials for the siege; and so far there was not a sign of them. "The principal object is to have what is wanted and to have it in time," Murray had written to Dundas in July; and Dundas had replied that he was preparing artillery for Dun-
