clock for a great attack on La Haye
Sainte by D'Erlon's corps of nearly 20,000 men. But a delay occurred
owing to a cause that we must now describe.

Before his great battery of eighty guns belched forth at the centre
and blotted out the view, he swept the horizon with his glass, and
discerned on the skirts of the St. Lambert wood, six miles away, a
dark object. Was it a spinney, or a body of troops? His staff officers
could not agree; but his experienced eye detected a military
formation. Thereupon some of the staff asserted that they must be
Bluecher's men, others that they were Grouchy's. Here he could scarcely
be in a doubt. Not long after 10 a.m. he received from Grouchy a
despatch, dated from Gembloux at 3 a.m., reporting that the Prussians
were retiring in force on Brussels to concentrate or to join
Wellington, and that he (Grouchy) was on the point of starting for
Sart-a-Walhain and Wavre. He said nothing as to preventing any flank
march that the enemy might make from Wavre with a view to joining
their allies straightway. Therefore he was not to be looked for on
this side of Wavre, and those troops must consequently be
Prussians.[511]

All doubts were removed when a Prussian hussar officer, captured by
Marbot's vedettes near Lasne, was brought to Napoleon. He bore a
letter from Buelow to Mueffling, stating that the former was on the
march to attack the French right wing. In reply to Napoleon's
questions the captain stated that Buelow's whole corps was in motion,
but wisely said nothing about the other two corps that were following.
Such as it was, the news in no way alarmed the Emperor. As Buelow was
about to march against the French flank, Grouchy must march on his
flank and take his corps _en flagrant delit_. That is the purport of
the postscript added to a rather belated reply that was about to be
sent off to Grouchy at 1 p.m. It did not reach him till 5 p.m., too
late to influence the result, even had he desisted from his attack on
Wavre, which he did not.[512]

We return to the Emperor's actions at half-past one. Dumont's and
Subervie's light horsemen were sent out towards Frischermont to
observe the Prussians; the great battery of eighty guns, placed on the
intermediate rise, now opened fire; and under cover of its deadly
blasts D'Erlon's four divisions dipped down into the valley. They were
ranged in closely packed battalions spread out in a front of some two
hundred men, a formation that Napoleon had