Such effects, by such use of superior numbers, without which they cannot be accomplished, are always the object of war, which aims not at fighting, but at results.
To estimate duly the operation, regard must be had to the impediments to movement, the overcoming of which gave success.

The larger force, to compass its object, had to reach secretly and rapidly positions which interposed decisively between the inferior and its line of communications and retreat.

To do this secretly, a large circuit must be made; that is, a road must be taken far beyond the enemy's ken, therefore much longer than that he himself would traverse to pass the same decisive points {p.292} and thereby evade interception.

The question is one of exterior and interior lines, and therefore of speed.

Speed in a country without resources, and especially when opposed to an enemy notoriously mobile, means not only hard legging and much privation, but very high organisation of transport, to insure even a bare sufficiency of support.
By virtue of the interior line, notwithstanding the rapidity with which Roberts' men and horses moved, Cronje got past the decisive points; but for French he might have escaped.