When morning broke, Marlborough dispatched forty squadrons of horse in pursuit of the fugitives towards Ghent, sent off Count Lottum with thirty battalions and fifty squadrons to carry the strong lines which the enemy had constructed between Ypres and Warneton, and employed the rest of his force in collecting and tending the wounded of both armies.

A few days later the two armies, that of Eugene and that of the Duke of Berwick, which had been marching with all speed parallel to each other, came up and joined those of Marlborough and Vendome respectively. The Duke of Berwick's corps was the more powerful, numbering thirty-four battalions and fifty-five squadrons, and this raised the Duke de Vendome's army to over 110,000, and placed him again fairly on an equality with the allies. Marlborough, having by his masterly movement forced Vendome to fight with his face to Paris, and in his retreat to retire still farther from the frontier, now had France open to him, and his counsel was that the whole army should at once march for Paris, disregarding the fortresses just as Wellington and Blucher did after Waterloo.

He was however, overruled, even Eugene considering such an attempt to be altogether too dangerous, with Vendome's army, 110,000 strong, in the rear; and it must be admitted it would certainly have been a march altogether without a parallel.

Finding that his colleagues would not consent to so daring and adventurous a march, Marlborough determined to enter France, and lay siege to the immensely strong fortress of Lille. This was in itself a tremendous undertaking, for the fortifications of the town were considered the most formidable ever designed by Vauban. The citadel within the town was still stronger, and the garrison of 15,000 picked troops were commanded by Marshal Boufflers, one of the most skillful generals in the French army. To lay siege to such a fortress as this, while Vendome, with this army of 110,000 men, lay ready to advance to its assistance, was an undertaking of the greatest magnitude.

In most cases the proper course to have taken would have been to advance against and defeat Vendome before undertaking the siege of Lille; but the French general had entrenched his position with such skill that he could not be attacked; while he had, moreover, the advantage, that if the allies stood between him and France, he stood between them and their base, commanded the Scheldt and the canals from Holland, and was therefore in position to interfere greatly with the onerous operation of bringing up stores for the British army, and with the passage to the front of the immense siege train requisite for an operation of such magnitude as was now about to be undertaken, and for whose transport alone 16,000 horses were required.

[Chapter 23]: The Siege of Lille.

The British cavalry suffered less severely at Oudenarde than did those of the other allied nationalities, as they were during the greater portion of the day held in reserve; and neither Rupert nor any of his special friends in the regiment were wounded. He was, however, greatly grieved at the death of Sir John Loveday, who was killed by a cannonball at the commencement of the action. Two of the captains in the 5th were also killed, and this gave Rupert another step. He could have had his captain's rank long before, had he accepted the Duke's offer, several times repeated, of a post on his staff. He preferred, however, the life with his regiment, and in this his promotion was, of course, regular, instead of going up by favour, as was, and still is, the case on the staff.

The train for the siege of Lille was brought up by canal from Holland to Brussels; and although the French knew that a large accumulation of military stores was taking place there, they could not believe that Marlborough meditated so gigantic an undertaking as the siege of Lille, and believed that he was intending to lay siege to Mons.

Berwick, with his army, which had since his arrival on the scene of action been lying at Douai, now advanced to Montagne; and Vendome detached 18,000 men from his army, lying between Ghent and Bruges, to Malle, to intercept any convoy that might move out from Brussels.

Marlborough's measures were, however, well taken. Eugene, with twenty-five battalions and thirty squadrons, moved parallel to the convoy, which was fifteen miles in length; while the Prince of Wurtemburg, General Wood, the Prince of Orange, each with a large force, were so placed as to check any movement of the enemy.