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General Zieten, in the campaign of 1815, with a view to check the advance of Napoleon and to enable Blucher and Wellington to effect their junction at Quatre Bras. It is an apt example, though Zieten can scarcely be said to have accomplished his main purpose.
With two brigades, each of 8000 men, he managed, indeed, in a country more than commonly free from obstacles, so to restrain two columns, one 45,000, the other 60,000 strong, that in a long summer's day they succeeded in accomplishing a forward march of not more than four or five miles; but he could not prevent the battle of Ligny, which Blucher was constrained to fight, while his own troops were as yet imperfectly concentrated and his communications with the English incomplete. Had Colonel Hamley taken his example from the Duke's daring exploit at Elbodon, he would have served his immediate purpose quite as well, and perhaps shown still more clearly than he does how much a small force well handled may effect in frustrating the purposes of a very superior enemy.
His second lesson receives its illustration from a masterly yet concise review of the campaign of 1796 in Italy, at the opening of which, from either side of the mountains of North Italy, the French and the Austrians and Sardinians, the two latter in alliance, threatened one another. On the western face of these mountains two armies, each about 20,000 strong, neutralised each other. On the southern side of the theatre of war Napoleon, with about 40,000, manoeuvred to take at a disadvantage the combined Austrian and Sardinian 'armies, numbering about 50,000. We must refer our readers to the volume before us for a sufficiently clear account of the various movements which enabled Napoleon to push the divisions of Augereau, Massena, and La Harpe between the 20,000 Sardinians and the 30,000 Austrians. The results were most decisive. The Austrians, mistaking the object of the enemy's advance, moved away from their allies in order to secure their own left, while Napoleon, keeping them occupied by repeated blows from smaller bodies, concentrated the bulk of his army against the Sardinians, and overwhelmed them. Another example of the same order of things is afforded in the history of the campaign of Eckmuhl in 1809. The masses engaged were on that occasion larger, and the Austrians had the Archduke Charles to direct them, but the general issues were the same, subject only to just such variations as the nature of the country and the character of the leaders of the respective armies might be expected to produce. On both occasions Napoleon succeeded in restraining a superior with an inferior force, while he marched
his superior force against the inferior force of his enemy. He pierced the Austrian centre, and destroyed both wings. Colonel Hamley thus sums up his able and elaborate commentary on the operations :
To sum up the effects of a successful operation of this kind, it appears
1. That either part of the separated army which stands to fight may find itself exposed to the blows of the full force of the antagonist, minus a detachment left to maintain the other part; as is seen by the examples of Millesiino, Ceva, and Eckmuhl.
* 2. That by alternating such blows, the assailant may continue both to weaken his antagonist and to interpose between the parts.
3. That as the commander of a separated part of an army will be playing the enemy's game if he stands to fight, his best course will be to retreat for re-union; and that this will be best effected by taking advantage of every position to retard the enemy on both lines.
4. That a commander who perceives an opportunity for separating the enemy and overwhelming a portion of his force, need not, generally, be solicitous to cover his own communications during the operation, since the enemy will be in no condition to assail them.
• Lastly. It is necessary to remark that the force which aims at séparating the parts of an enemy should be so superior to either part singly as to preserve a superiority after detaching a force in pursuit of the portion first defeated ; and that if the attacking force does not fulfil this condition, it will have no right to expect success.'
The illustrations of the third incident,--the case of independent against combined lines of operation, are taken from the Archduke Charles' campaign of 1796 in Germany, and the campaigns of 1861-62, both in Virginia, during the late civil war in America. We cannot pretend to analyse either; if, indeed, a narrative so terse and clear as that of Colonel Hamley would admit of analysis; but the moral to be gathered from it is this, that the army which operates on a common centre against widely separated bodies advancing upon that centre, possesses immense advantages. It can confront one or more lines of invasion with a retarding though inferior force, while it brings a preponderating force into action on the other; or if threatened from three or four quarters at once, it can treat the rest as wings, while the bulk of its own strength, held in reserve, is ready to fall upon the first of the enemy's columns which breaks through. It was the neglect of this great principle which cost General Benedek so dear, and a wise adherence to it which enabled Johnston and Lee on two separate occasions to save Richmond, and beat back the enormously superior forces which threatened it. At the same time many points must be well considered before a general commits himself to this line of
action. He must take care, for example, not to keep his reserves too far in rear of his retarding corps, otherwise the enemy will have had time to extricate himself from some of them before the great blow can be struck, and the numbers employed on operations of delay must be adequate, and not more than adequate, to the purposes which they are meant to serve. But above all, the leader who adopts this order of strategy must be bold, prompt, and strong of purpose. Indecision or slowness cannot fail in such circumstances to prove fatal, for only by hard blows struck often and at the proper moment can an inferior army hope to obtain any advantages over a superior.
Colonel Hamley's fourth incident, the case of combined armies operating from divergent bases, is illustrated by a clear, impartial, and intelligible sketch of the campaign of Waterloo. The Prussians and the English had in covering Brussels to keep open their respective communications with Cologne, through Liège on the one side, and on the other through Ostend and Antwerp with the sea. Their front was necessarily much extended, and they found themselves called upon to protect, not only the great roads which lead from behind the French fortresses to Brussels, but all the lesser roads which linked them to their own bases. It was open to Napoleon to attack them by his right, in which case he would fall upon the Prussian communications through Liège; or by his left between the Lys and the Scheldt, in which case he would interpose between the English and Ostend ; or finally he might take one of the three great roads leading direct upon Brussels, in which case the blow would be directed to break through between them. He actually adopted the third alternative, and wellnigh achieved his purpose ; indeed, his failure must be attributed at least as much to time lost on his side, and tactics full of faults, as to the rapidity and decision with which his opponents repaired the damage which they had sustained at the battle of Ligny. How this was done we need not stop to explain; yet let the military reader bear in mind that it is not every army which will sustain, without flinching, such a combat as that to which the English were committed on the 18th of June; and that, had they been defeated before the Prussians arrived on the ground, Blucher's case would have been desperate. On the other hand, two armies operating from divergent bases, if, as in this case, they surmount the difficulty of their position, strike home upon the concentrated force fairly committed against one of them with tremendous force. It was so when, about half-past seven in the evening of the 18th of June, Blucher fell upon the flank and rear of the French, already exhausted. With them defeat was at once
converted into rout, from which there was no rallying. Hence our author justly draws the conclusion :
If, then, allied armies operating from divergent bases can combine, their operation will be more effective than if they had a common base. But from the moment that their concert is destroyed by the interposition of an adequate force, the chances are against them.'
The case of dislodging an army by operating with a detachment against its rear, is exemplified in the campaign of 1864 in Georgia. The object of Sherman was to seize, and of Johnston to retain Atlanta. It is an operation which ought never to be attempted, unless, as in the instance cited by our author, the assailant be greatly superior in numbers to his adversary. Sherman's army numbered not less than 100,000 combatants. Johnston could oppose to them only 40,000, which he latterly increased to 54,000. There was, therefore, no risk to Sherman keeping 50,000 in hand, when he detached first 25,000, and ultimately 50,000 under Macpherson, with orders to double round Johnston's flank, and come in upon his rear at Resaca. Perhaps, indeed, had Johnston left a single division, say 10,000 men, to hold his fortified position, and fallen with the rest upon Macpherson while as yet his force numbered only 25,000, he might have baffled a movement which, when the 25,000 grew into 50,000, became irresistible. Be this, however, as it may, his great superiority of numbers, as it justified the strategy of the Federal commander, so it enabled him to command success in a campaign on the issues of which the war, as the event proved, absolutely turned. In like manner the Duke of Wellington, making his grand advance from the Douro to the Ebro, did not hesitate to detach Lord Hill, with half his army, to operate on the enemy's flank. Neither his success, however, nor that of Sherman, will bear out any other commander in venturing on an experiment so critical, unless he know that he is strong enough to fight with either portion of his army, whatever force the enemy may be able to bring against him.
The general who is about to engage in military operations, as well as the government which sends him forth, ought to be well acquainted with every feature of the country which is about to become the theatre of war. Unless this knowledge be present with both, the one may provide at enormous cost an equipment for the army which is useless, and the other will find himself confronted from time to timė by obstacles of the most serious description. A well-appointed topographical department becomes thus essential to the efficiency of every war office, and the
best maps which can be procured must form part of the equipment of general and other officers in the field. There are scarcely two countries in the world which present exactly the same military features. North Italy, for example, is a basin almost entirely surrounded by mountains, which pour down concentrically frequent streams, collecting in the Po. Spain is the very reverse, for there the ground rises from the seaboard towards the centre, sending off its waters east and west. In the theatre of war during the late American conflict, the great feature was the line of the Alleghanies intersecting the Southern States, and sending its streams right and left into the Atlantic and the Mississippi. A knowledge of facts of this sort is necessary in order to enable a general to make his arrangements, since it is obvious that a plan which might serve for North Italy would not serve for Spain ; nor could a plan suitable for either be of any avail in Virginia and Maryland. Neither may any safe inference be drawn from what officers see at home to what they are certain to encounter abroad. In England the country is highly cultivated, arable and pasture continually intermingling, of which the results are frequent fences, open ditches, copses, woods, and a few bare plains. Armies can move in such a country only along the roads, and it would not be easy to find spaces at pleasure in which they could form in order of battle, Belgium and the east of France are, on the other hand, rolling plains. Hungary is a huge corn-field, with enormous prairies lying contiguous to it. Now a general must consider all this, and make his arrangements with a view to the capabilities that are presented to him. He would not carry swarms of cavalry into the Apennines or the Pyrenees. He would not overload himself with artillery and waggons in Spain, where the roads are narrow and easily choked. Belgium and Hungary, and the great plain of Germany, offer, on the contrary, immense facilities for both cavalry and artillery, and enable infantry to move in order of battle over the fields. All these points must be considered by a general in making his strategical arrangements. So must the configuration of the frontier which he is called upon to protect, or against which his movements are to be directed. To England an extensive sea-coast is everything. Had not the French possessed themselves of all the northern and eastern fortresses of Spain, an English army operating from these would have interposed at once between the enemy and their communications. As it was, Wellington was obliged to make Portugal his base till circumstances enabled him to strike for a better, after which all the passes, through the Pyrenees became closed to the enemy. If the Austrians in the late war