When you are dealing with many miles of men whose armament is not only destructive at a great distance, but also over a wide belt of ground, you have, in the first place, a vast extension of any possible defensive lines. It is in this, perhaps, that the present war is most sharply distinguished from the wars of the past; and I mean by the wars of the past the wars of no more than a generation ago.
There have been plenty of long defensive lines in the past. Generals desiring to remain entirely upon the defensive, for any reason, over an indefinite space of time (for no one can remain on the defensive for ever), have constructed from time immemorial long lines behind which their men, though very thinly spread out, could hold against the enemy.
They have been particularly led to do this since the introduction of firearms, because firearms give the individual man a wider area over which he can stop his enemy. But in every form of war, primitive or modern, these great lines have existed.
The Wall of China is one great instance of them; the Roman Wall over the North of Britain, from sea to sea, is another; and the long-fortified Roman frontier from the Rhine to the Danube was a third.
The generals of Louis XIV, in a line called by the now famous name of La Bassée, established on a smaller scale the same sort of thing for a particular campaign. There are hundreds of examples. But the characteristic novelty of the present war, and the point in which it differs from all these ancient examples, is the _rapidity_ with which such lines are established by the great numbers now facing each other, armed as they are by weapons of very long range.
[Illustration: This gives you at a glance an idea of the numbers engaged and the time occupied in some famous battles of the past. Each little figure in the above drawings represents 5000 men. It will be seen that even the Battle of Mukden is scarcely comparable in duration with the months-long contests of the present war.]
Forty-eight hours’ preparation, or even less, is enough for troops to “dig themselves in” over a stretch of country which, in the maximum case of the French lines, is 300 miles in extent. Every slight advance is guaranteed by a new construction of trenches, every retirement hopes to check the enemy at another line of trenches established at the rear of the first.