The 27th was passed without a movement, Villars refusing to leave his entrenchments, and the commanders of the allies giving no hint of their next intention. But during that same day Tilly with the Dutch had appeared before Tournai. On the evening of the day Marlborough himself was before the town. On the 28th Prince Eugene joined both the Dutch and Marlborough before the town, taking up his headquarters at Froyennes, Marlborough being at Willemeau, and the Dutch, under Tilly, already established on the east of Tournai from Antoing to Constantin, just opposite Eugene, where they threw a bridge across the Scheldt. By the evening of the 28th, therefore, Tournai was invested on every side, and the great allied armies of between 110,000 and 120,000 men had abandoned all hope of carrying Villars' lines, and had sat down to the capture of the frontier fortress.[2]
A comprehension of this siege of Tournai, which so largely determined the fortunes of the campaign of Malplaquet, will be aided by the accompanying sketch map. Here it is apparent that Marlborough with his headquarters at Willemeau, Eugene with his at Froyennes, the Dutch under Tilly in a semicircle from Antoing to Constantin, completed the investment of the fortress, and that the existing bridge at Antoing which the Dutch commanded, the bridge at Constantin which they had constructed, giving access over the river to the north and to the south, made the circle complete.
[Illustration: Sketch Map showing complete investment of Tournai.]
The fortifications of Tournai were excellent. Vauban had superintended that piece of engineering in person, and the scheme of the fortifications was remarkable from the strength of the citadel which lay apart from the town (though within its ring of earthworks) to the south. The traveller can still recognise in its abandonment this enormous achievement of Louis XIV.'s sappers, and the opposition it was about to offer to the great hosts of Marlborough and Eugene does almost as much honour to the genius of the French engineer as to the tenacity of the little garrison then defending it.
Two factors in the situation must first be appreciated by the reader.
The first is that the inferiority of Villars' force made it impossible for him to do more than demonstrate against the army of observation. He was compelled to leave Tournai to its fate, and, indeed, the king in his first instructions, Villars in his reply, had taken it for granted that either that town or Ypres would be besieged and must fall. But the value of a fortress depends not upon its inviolability (for that can never be reckoned with), but upon the length of time during which it can hold out, and in this respect Tournai was to give full measure.