Flanders
Flanders shares its borders with Wallonia in the south, Brussels being an enclave within the Flemish Region. The rest of the border is shared with the Netherlands (Zeelandic Flanders in Zeeland, North Brabant and Limburg) in the north and east, and with France (French Flanders in Hauts-de-France) and the North Sea in the west. Voeren is an exclave of Flanders between Wallonia and the Netherlands, while Baarle-Hertog in Flanders forms a complicated series of enclaves and exclaves with Baarle-Nassau in the Netherlands. Germany, although bordering Wallonia and close to Voeren in Limburg, does not share a border with Flanders. The German-speaking Community of Belgium, also close to Voeren, does not border Flanders either. (The commune of Plombières, majority French speaking, lies between them.)
Battle of the Yser
Part of northern France and the north Belgium from the Pas-de-Calais to the Scheldt estuary had been known as Flanders since the eleventh century. West of a line between Arras and Calais in the north of France, lie chalk downlands covered with soil sufficient for arable farming and east of the line, the land declines in a series of spurs into the Flanders plain. By 1914, the plain was bounded by canals linking Douai, Béthune, Saint-Omer and Calais. To the south-east, canals run between Lens, Lille, Roubaix and Courtrai, the Lys river from Courtrai to Ghent and to the north-west lies the sea. The plain is almost flat, apart from a line of low hills from Cassel, east to Mont des Cats, Mont Noir, Mont Rouge, Scherpenberg and Mount Kemmel. From Kemmel, a low ridge lies to the north-east, declining in elevation past Ypres through Wytschaete, Gheluvelt and Passchendaele, curving north then north-west to Dixmude where it merges with the plain. A coastal strip about wide, is near sea level and fringed by sand dunes. Inland the ground is mainly meadow, cut by canals, dykes, drainage ditches and roads built up on causeways. The Lys, Yser and the upper Scheldt have been canalised and between them the water level underground is close to the surface, rises further in the autumn and fills any dip, the sides of which then collapse. The ground surface quickly turns to a consistency of cream cheese and on the coast troop movements were confined to roads, except during frosts.