The allies had been caught unprepared. But as soon as Bliicher got the first real warning of imminent danger he ordered the immediate concentration of his army at Sombreffe. Unfor tunately, the orders sent to Billow were so hazy that Billow did not realize the need for any special haste. Thus the IV. Corps was neutralized until after the i6th. But Pirch I. and Thielemann acted with satisfactory promptness and their corps reached Mazy and Namur by nightfall. Blucher in pursuance with his plan moved to Sombreffe.
Wellington's position at night was hardly safe or even satis factory. It was not until 3 P.M. that definite news of the French advance reached Brussels, and even then the duke was not certain of the direction of Napoleon's main stroke. Consequently he ordered his divisions to concentrate at their alarm-posts and await further orders. The danger of BlUcher's position was thus enormously increased. The allies do not appear to have decided upon the course to be taken in case they were surprised, and their system of inter-communication was most imperfect. Luckily Wellington's subordinates at the critical point acted with ad mirable boldness. Prince Bernard, commanding the brigade at Quatre Bras, retained his position there to check the French advance instead of drawing off to mass with his division at Nivelles. His immediate superiors approved his action. Owing to these officers Wellington retained possession of the important strategical point of Quatre Bras. Consequently Ney's advance struck into Prince Bernard's advanced troops who were forced back. But Prince Bernard firmly held his main position at the cross-roads; and, as the day was drawing on, Ney wisely decided not to push on any farther and so risk isolating the left wing. He
halted and reported to the emperor.
Meanwhile Grouchy and Vandamme wasted two hours deliberat ing in front of the Prussian brigade at Gilly. Then at 5:3o P.M. Napoleon again reached the front and vigour replaced indecision. After a brief cannonade Vandamme advanced with the bayonet and the Prussians gave way. Grouchy then moved on Fleurus and halted for the night.
Owing to Zieten's skill Blucher had secured his concentration area, one corps was in position, and two others were at hand. Thanks to his subordinates Wellington still retained a grip on Quatre Bras. His corps were assembling : I., Nivelles, Braine le Comte, Enghien; II., Ath, Grammont, Sotteghem; Cavalry, Ninove ; Reserve, at Brussels. During the night the divisions were ordered to move to Nivelles, and at dawn the Reserve marched for Mt. St. Jean.
The duke had relied on information that did not come to hand. His intelligence officer, Colonel Colquhoun Grant, who was in France, was ordered to send back his reports to the duke through General Dornberg at Mons. On June 15 Grant reported that the French Army was advancing, but Dornberg refused to believe the report and returned it. Owing to this officer's presumptuous folly Grant's report only reached Wellington on June 18.
On the night of the r5th the "Armee du Nord" was disposed as follows:—Left Wing, Frasnes to Marchienne ; Right Wing, in front of Fleurus and astride the Sambre at Chatelet; Centre (or Reserve), Guard, between Gilly and Charleroi; but Milhaud's Cuirassiers and Lobau's (VI.) Corps were still south of the Sambre. Thus, despite the delays, Napoleon had secured a dominant strategical position. The allies were still encouraged to attempt a risky forward concentration, whilst Napoleon's cover ing forces were sufficiently far forward to be able to grip which ever ally adventured his army first. The "Armee du Nord" lay concentrated "in a square whose sides measured 12 m. each; and it could with equal facility swing against the Prussians or the Anglo-Dutch, and was already placed between them." 16th June.—Early in the morning Prince Bernard was rein forced at Quatre Bras by the rest of his division (Perponcher's) ; and Wellington's other troops were now all on the march east ward except the reserve, who were heading southwards and halted at the cross-roads of Mt. S. Jean until the duke had resolved that their objective should be Quatre Bras. They then marched in that direction. Blucher meanwhile was making his arrangements to hold a position to the south of the Namur-Nivelles road and thus maintain uninterrupted communication with Wellington at Quatre Bras.