Such were the only battles that they knew; no invader had ever ventured among them. Invasion, indeed, seemed physically impossible. The whole country between the hills of Cassel, Dixmude, and the line of sand-hills along the coast is but a vast _schoore_, a huge polder snatched from the sea, and almost entirely below the sea-level, owing to the deposits of mud left high and dry on the shore. Down to the eleventh century it was still a bay into which the _drakkars_ of the Norse pirates might venture. If Dixmude, like Penmarc'h and Pont-Labbé, had retained its maritime character, we might have found on the fronts of its riverside houses the rusty iron rings to which barques were once moored. To safeguard the tenure of this uncertain soil, slowly annexed by centuries of effort, conquered, but not subdued, and always ready to revert to its former state, it was not enough to thrust back the sea, which would have overflowed it twice a day at high tide; it was further necessary to drain off the fresh water, which streams down into it from the west and the south, mainly from the stiff clay of the Dutch hills, floods the meadows, cuts through the roads, and invades the villages. The struggle is unintermittent. Such country, threatened on every side, is only habitable by virtue of incessant precautions and watchfulness. The sea is kept under control by Nieuport, with its formidable array of sluices, locks, chambers, water-gates, and cranks; the fresh water, which oozes out on every hand, spangling the rough homespun of the glebe with diamond pools from the beginning of autumn to long after the end of winter, is dealt with by a methodical and untiring system of drainage directed, under State control, by associations of farmers and landowners (_gardes wateringues_). Hence the innumerable cuttings (_watergands_) along the hedges, the thousands of drains that chequer the soil, the dykes, several metres high, which overhang the rivers--the Yser, the Yperlee, the Kemmelbeck, the Berteartaart, the Vliet, and twenty other unnamed streams of inoffensive aspect--which, when swelled by the autumn rains, become foaming torrents rushing out upon the ancient _schoore_ of Dixmude. The roads have to be raised very high in this boundless marsh land, the depressed surface of which is broken only by sparse groups of trees and the roofs of low-lying farms. They are few in number, only just sufficient to ensure communication, and they require constant repair. Torn up by shells and mined by the huge German explosives, the "saucepans" (_marmites_) and "big niggers" (_gros noirs_), as the sailors call them, our company of French and Belgian road-menders had to work day and night throughout the operations to keep them open.