d Corps had its headquarters at Ciney in the Ardennes, and was
scattered in various posts throughout that forest, its furthest cantonment
being no nearer than Dinant, which, by the only good road available, was
nearer forty than thirty miles from Napoleon's point of attack.

Finally, the Fourth Corps was as far away as Liege (nearer fifty than
forty miles by road from the last cantonment of the First Corps), and
having its various units scattered round the neighbourhood of that town.

Napoleon, therefore, attacking Charleroi suddenly, imagined that he would
have to deal only with the First Corps at Charleroi and its neighbourhood.
He did not think that the other three corps had information in time to
enable them to come up westward towards the end of the line and meet him.
The outposts of the First Corps had, of course, fallen back before the
advance of the Emperor's great army; the mass of that First Corps was, he
knew, upon this morning of the 16th, some mile or two north and east of
Fleurus, astraddle of the great road which leads from Charleroi to
Gembloux. At the very most, and supposing this First Corps (which was of
33,000 men, under Ziethen) had received reinforcements from the nearest
posts of the Second and the Third Corps, Napoleon did not think that he
could have in front of him more than some 40,000 men at the most.

He was in error. It had been arranged among the Prussian leaders that
resistance to Napoleon, when occasion might come for it, should be offered
in the neighbourhood of the cross-roads where the route from Charleroi to
Gembloux crosses that from Nivelles to Namur. In other words, they were
prepared to stand and fight between Sombreffe and the village of Ligny.
The plan had been prepared long beforehand. The whole of the First Corps
was in position with the morning, awaiting the Emperor's attack. The
Second Corps had been in motion for hours, and was marching up during all
that morning. So was the Third Corps behind it. Blucher himself had
arrived upon the field of battle the day before (the 15th), and had
written thence to his sovereign to say that he was fully prepared for
action the next day.

Indeed, Blucher on the 15th confidently expected victory, and the end of
the campaign then and there. He had a right to do so, for Napoleon's
advance had been met by so rapid a concentration that, a little after noon
on that Friday the 16th, and before the first shots were fired, well over
80,000 men