Prince therefore at once pushed on. Rain was falling in torrents, and the roads were like rivers, but he continued his advance eastward, behind the woods that line the Haine, almost without a halt, till at
Aug. 26./Sept. 6. length at two o'clock on the morning of the 6th of September he wheeled to the right and crossed the river at Obourg three miles to the north-east of Mons. Before him lay the river Trouille curving round to the south by Mons, and in rear of it a line of entrenchments, thrown up during the last war, from Mons to the Sambre, to cover the province of Hainault. A short survey showed him that the lines were weakly guarded; and before noon he had passed them without opposition. His force, notwithstanding the weather and the state of the roads, had traversed the fifty miles to Obourg in fifty-six hours.
Too late Villars discovered that for the second time he had been duped, and that Marlborough had no intention of forcing his way into France through the lines of La Bassée and the wet swampy country beyond them, when he could pass the lines of the Trouille without loss of a man. He was in a difficult position, for Mons was slenderly garrisoned and difficult of access, though, if captured, it would be a valuable acquisition to the Allies. The approach to it from the westward was practically shut off by a kind of natural barrier of forest, running, roughly speaking, from St. Ghislain on the Haine to the north to Maubeuge on the Sambre to the south. In this barrier there were but two openings, the Trouée de Boussut between the village of that name and the Haine, and the Trouées d'Aulnois and de Louvière, which are practically the same, some miles further to the south. These will be more readily remembered, the northern entrance by the name of Jemappes, the southern by the name of
