The whole of the four days of 1815, and the issue of Waterloo itself, turned upon Erlon’s disastrous counter-marching between Quatre Bras and Ligny upon this Friday, the 16th of June, which was the decisive day of the war.
What actually happened has been sufficiently described. The useless advance of Erlon’s corps d’armée towards Napoleon and the right—useless because it was not completed; the useless turning back of that corps d’armée towards Ney and the left—useless because it could not reach Ney in time,—these were the determining factors of that critical moment in the campaign.
In other words, Erlon’s zigzag kept the 20,000 of the First Corps out of action all day. Had they been with Ney, the Allies under Wellington at Quatre Bras would have suffered a disaster. Had they been with Napoleon, the Prussians at Ligny would have been destroyed. As it was, the First Army Corps managed to appear on neither field. Wellington more than held his own; the Prussians at Ligny escaped, to fight two days later at Waterloo.
Such are the facts, and they explain all that followed (see Map, [next page]).
But it has rightly proved of considerable interest to historians to attempt to discover the human motives and the personal accidents of temperament and misunderstanding which led to so extraordinary a blunder as the utter waste of a whole army corps during a whole day, within an area not five miles by four.
It is for the purpose of considering these human motives and personal accidents that I offer these pages; for if we can comprehend Erlon’s error, we shall fill the only remaining historical gap in the story of Waterloo, and determine the true causes of that action’s result.
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There are two ways of appreciating historical evidence. The first is the lawyer’s way: to establish the pieces of evidence as a series of disconnected units, to docket them, and then to see that they are mechanically pieced together; admitting, the while, only such evidence as would pass the strict and fossil rules of our particular procedure in the courts. This way, as might be inferred from its forensic origin, is particularly adapted to arriving at a foregone conclusion. It is useless or worse in an attempt to establish a doubtful truth.