From this result it follows that, if we are not very close to the enemy, and have a suitable advanced guard we might remain in cantonments, even if the enemy is concentrated, as Frederick the Great did at Breslau in the beginning of the year 1762, and Buonaparte at Witebsk in 1812. But although by preserving a right distance and by suitable arrangements we have no reason to fear not being able to assemble in time, even opposite an enemy who is concentrated, yet we must not forget that an army engaged in assembling itself in all haste can do nothing else in that time; that it is therefore, for a time at least, not in a condition to avail itself in an instant of fortuitous opportunities, which deprives it of the greater part of its really efficient power. The consequence of this is, that an army should only break itself up completely in cantonments under some one or other of the three following cases:
1. If the enemy does the same.
2. If the condition of the troops makes it unavoidable.
3. If the more immediate object with the army is completely limited to the maintenance of a strong position, and therefore the only point of importance is concentrating the troops at that point in good time.
The campaign of 1815 gives a very remarkable example of the assembly of an army from cantonments. General Ziethen, with Blücher’s advanced guard, 30,000 men, was posted at Charleroi, only two miles from Sombreff, the place appointed for the assembly of the army. The farthest cantonments of the army were about eight miles from Sombreff, that is, on the one side beyond Ciney, and on the other near Liége. Notwithstanding this, the troops cantoned about Ciney were assembled at Ligny several hours before the battle began, and those near Liége (Bulow’s Corps) would have been also, had it not been for accident and faulty arrangements in the communication of orders and intelligence.
Unquestionably, proper care for the security of the Prussian army was not taken; but in explanation we must say that the arrangements were made at a time when the French army was still dispersed over widely extended cantonments, and that the real fault consisted in not altering them the moment the first news was received that the enemy’s troops were in movement, and that Buonaparte had joined the army.
Still it remains noteworthy that the Prussian army was able in any way to concentrate at Sombreff before the attack of the enemy. Certainly, on the night of the 14th, that is, twelve hours before Ziethen was actually attacked, Blücher received information of the advance of the enemy, and began to assemble his army; but on the 15th at nine in the morning, Ziethen was already hotly engaged, and it was not until the same moment that General Thielman at Ciney first received orders to march to Namur. He had therefore then to assemble his divisions, and to march six and a half miles to Sombreff, which he did in 24 hours. General Bulow would also have been able to arrive about the same time, if the order had reached him as it should have done.
But Buonaparte did not resolve to make his attack on Ligny until two in the afternoon of the 16th. The apprehension of having Wellington on the one side of him, and Blücher on the other, in other words, the disproportion in the relative forces, contributed to this slowness; still we see how the most resolute commander may be detained by the cautious feeling of the way which is always unavoidable in cases which are to a certain degree complicated.
Some of the considerations here raised are plainly more tactical than strategic in their nature; but we have preferred rather to encroach a little than to run the risk of not being sufficiently explicit.