So retreat was unavoidable, and was begun at 10 a.m. on the 17th. Wellington was to fall back on the known position of Waterloo. Blucher had promised to come with his whole army if he could. Napoleon had despatched Grouchy with 33,000 men to prevent this, and keep the Prussians on the move; but the emperor’s own ill health and failing strength had again caused delay; so Grouchy started late, and Napoleon wasted his time in rest and a review. The British retreat was well conducted in wretched weather, and despite the heavy ground, there was some rearguard fighting, chiefly by the cavalry on both sides. At length, on the sodden ground about Mont St. Jean, both armies settled down for what rest was possible, and waited for the dawn. Thus the British prepared for battle, with the hope that Blucher, or the certainty that night, would come on the 18th June 1815. But still, with a firmness that seems degenerating into obstinacy, Wellington persisted in his nervous anxiety for his right flank, as he had done throughout, and stationed some 10,000 men out of his small army at Hal. His excuse that the troops were inferior is futile, for he had battalions of a precisely similar character on the battlefield of Waterloo. He must have known, from the extent of front occupied, that the bulk of the French army were in front of him. He must have guessed that some considerable force had been despatched to keep the defeated Prussians on the move. He knew that the distance of Hal was such as to preclude the possibility of any further considerable detachment from the main French army being made, as it would be entirely isolated from the main battle. His force was none too strong to hold the position till Blucher came. His centre was weak and reserves were insufficient. By ten o’clock, thinks Shaw Kennedy, “it is difficult to understand how any fear for the Hal road could have existed.” None the less he left ten thousand men, under the Prince of Orange, not only unemployed, but likely to remain unemployed. There, unfortunately for them, were left a brigade of Dutch Belgians and one of Colvile’s Division, that of Johnston, comprising the 35th, 54th, 59th, and 91st Regiments.