he thrust them at once into the opening, telling their brave captain, Tew, that he was to block up that entrance; to die there if it must be, never to give way! And well did the gallant fellow obey his orders; he died there, but the opening was defended. The great disparity of numbers was thus abated, and the action of six thousand men paralysed by the more skilful action of only eighty! It was on a smaller scale as to numbers, a stroke of generalship like that which won Blenheim for the Duke of Marlborough."

In this example the opening in the wall was the defile, by taking post behind which eighty men held in check 6000! Sir C. Napier made use of the defile to apply Maxim 19.

Maxim 30.-Every disadvantage may be removed by skill or fortune, except Time. If a general has

Time against him he must fail.
Time is the best ally.

*

And conversely,

Napier's "Conquest of Scinde."

CHAP. V.

LINES OF DEFENCE.

LINES of defence are natural and artificial.

Of the first are deserts, mountain-ranges, great rivers, and dense forests.

In general, the frontier line which divides one country from another is formed by some one of the above-named obstacles, or a combination of them.

That which presents the greatest difficulty to an invading army is a desert, on account of the immense transport which must accompany it to carry water and provisions, because of the few tracks by which it can be passed (which are determined by the position of the wells), and moreover because of the opposition to be encountered from the elements in those regions where deserts are found. As an example of the difficulties of such an operation in our own times and by our own troops, and of genius in surmounting them, see the account of Sir Charles Napier's eight days' march across the desert of Scinde for the purpose of destroying the Ameer's fortress of Emaum Ghur.*

* 66 Conquest of Scinde," 1st chapter, 2nd part.

Next in order come mountain-ranges; these can only be passed at certain known points, which can be watched by the defenders. The outlet of the passes which an invading army must traverse, may be occupied by small forts, and the valleys into which the passes admit, by fortresses.

Although a range of mountains is unquestionably a great obstacle, it is rarely an insurmountable one, unless defended by the mountaineers themselves, who know every path and track; where these are neutral, the best positions may, in general, be turned by paths unknown to the defenders. As an example of this may be cited an extract from the report of the Duke de Rohan, who was defending the Valteline against the Spanish and Austrian armies. In describing the position of his army he states, "In the present instance, although the flanks of the army were thought to be securely protected by the mountains as by so many fortresses, it was found to be exposed on all sides, and one opening was no sooner closed than two more were discovered; so that several armies in place of one would be required to defend this country." It was a maxim of Napoleon's that "where one man can set his foot a whole army may pass.'

The defence of any long line, however strong it may be generally, over which there are many practicable passages, is difficult in proportion to the

number of those passages. An invader, by threatening to advance on several of these points, may oblige the defenders to disseminate their forces and to guard each equally, while the mass of the invading army advances on that which has been originally selected.*

Dense forests are much on a par with mountains, or they may probably be more easily defended, since all the passages through them are known with greater certainty.

From what has been said, it is evident that the line of a great river is less easy of defence than a range of mountains, as affording a far greater number of points of passage.

It must be remarked, that lines of great natural obstacles are only "lines of defence" when they run across the line of operations of an aggressive force. When they run parallel to such line of operation they are, on the contrary, a great advantage to that force. Its flanks are supported on them; it may divide the enemy's attention and forces, by threatening to operate on both sides. In this case the passages over such obstacles are of great military importance, as affording the army the power of changing the side of operation at will. Here the advantage is generally

* It was in this manner that King Joseph passed the Sierra Morena after Ocana, when he invaded Andalusia.

with an invading army; for the object of the defensive force being to bar the progress of the enemy in a certain direction, it cannot change its side of operation without leaving open to the enemy the road by which he was advancing towards his object, unless such a change of side should enable the defenders to act offensively against the communications of the invading army.

The passes then by which mountain-ranges, and the bridges by which rivers, are crossed, whether those ranges and rivers cross the line of operations of an army or are parallel to it, are decisive strategical points of a high order.

Of course that army which is in possession of those passes or those permanent bridges which are defended by fortresses, has the advantage; but as regards rivers, an army which is provided with proper bridge trains possesses the power of passage at every point where it is not disputed by an enemy, at the expense of the delay necessary for the construction of the bridges.

Ulm, in the campaign of 1800, was a double têtede-pont, affording the Austrian marshal, Kray, a passage over the Danube from either bank, which river was parallel to the line of operations of the French and Austrian armies; and the manner in which Kray employed the possession of that point to hold Moreau in check illustrates this subject well.