Now the significance of such a conformation to the battlefield of Tourcoing lay in the fact that it was impossible for any considerable force to manœuvre between the third column (which was marching upon Roubaix) and the Marque River. Had the Marque not existed, Kinsky, with the fourth column, would have been free to march parallel with York, just as York marched parallel with Otto, while the Arch-Duke with his fifth column, instead of having been given a rendezvous right down south at Pont-à-Marcq (the point marked 5 on my sketch), would have gone up the main road from St Amand to Lille, and have marched parallel with Kinsky, just as Kinsky would have marched parallel with York. In other words, the fourth and the fifth columns, instead of being ordered along the dotted lines marked upon my sketch (the elbows in which lines correspond to the crossing places of the Marque), would have proceeded along the uninterrupted arrow lines which I have put by the side of them.
The Marque made all the difference. It compelled the fifth column to take its roundabout road, and the fourth, detained by the delay of the fifth, was held, as we shall see in what follows, for a whole day at one of the crossings of the river.
The little stream has a deep and muddy bottom, and the fields upon its banks are occasionally marshy. This feature has been exaggerated, as have the other features I have mentioned, in order to explain or excuse the defeat, but, at any rate, it prevented the use of crossing places other than bridges. The Marque has no true fords, and there is no taking an army across it, narrow as it is, save by the few bridges which then existed. These bridges I have marked upon the sketch.
So far as the terrain is concerned, then, what we have to consider is country, flat, but containing low defensive positions, largely cut up, especially between the Scheldt and Roubaix, by hedges and walls, though more open elsewhere, and particularly open towards the north: a serious obstacle to the advance of one body in the shape of the River Lys; and another obstacle, irritating rather than formidable in character, but sufficient both by its course and its marshy soil to complicate the advance, namely, the little River Marque.
As to the weather, it was misty but fine. The nights in bivouac were passed without too much discomfort, and the only physical condition which oppressed portions of the allied army consisted in the error of its commanders, and proceeded from fatigue.