which the advanced guard is detached is the same as the radius of the cantonments, and the point of assembly is fixed in the centre of the cantonments, the time which is gained by checking the enemy’s advance would be available for the transmission of intelligence and getting under arms, and would in most cases be sufficient, even although the communication is not made by means of signals, cannon-shots, etc., but simply by relays of orderlies, the only really sure method.
With an advanced guard pushed forward three miles in front, our cantonments might therefore cover a space of thirty square miles. In a moderately-peopled country there would be 10,000 houses in this space, which for an army of 50,000, after deducting the advanced guard, would be four men to a billet, therefore very comfortable quarters; and for an army of twice the strength nine men to a billet, therefore still not very close quarters. On the other hand, if the advanced guard is only one mile in front, we could only occupy a space of four square miles; for although the time gained does not diminish exactly in proportion as the distance of the advanced guard diminishes, and even with a distance of one mile we may still calculate on a gain of six hours, yet the necessity for caution increases when the enemy is so close. But in such a space an army of 50,000 men could only find partial accommodation, even in a very thickly populated country.
From all this we see what an important part is played here by great or at least considerable towns, which afford convenience for sheltering 10,000 or even 20,000 men almost at one point.
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