Fifth: Since Austria knew that Moreau's army was large, and that the Army of Italy was small, she believed that, by taking the defensive in Germany and the offensive in Italy, she could hold in check the larger army, while she overwhelmed the smaller with greatly superior numbers.
Consider for a moment the situation as it must have appeared at this time to Austria. Not aware of the existence of the Army of Reserve, she saw only Moreau's army along the Rhine, and Masséna's along the Apennines. Was it not reasonable to suppose that the one hundred and twenty thousand Austrians in Germany might hold in check Moreau's army of one hundred and thirty thousand, while the one hundred and twenty thousand Austrians in Italy destroyed the forty thousand French under Masséna?
On the other hand, there were several reasons why this plan should not have been adopted by the Aulic Council.
With the Army of Italy in possession of the Apennines and Maritime Alps, flanked on the right by the fortified city of Genoa, Masséna had the advantage of a strong defensive position. Without an enormous superiority in numbers, it was a difficult matter for Melas to drive back the French. And even should he succeed in this undertaking, there still remained the line of the Var, a strongly fortified position, flanked on the north by the Alps and on the south by the sea; a position which could neither be turned nor be forced, except with greatly superior numbers and desperate fighting.
To succeed offensively in Italy, the Austrians had therefore to outnumber greatly the French. The French superiority in position counterbalanced the Austrian superiority in numbers. The Austrian plan allowed Bonaparte with inferior forces to hold in check for a time a large Austrian army in Italy, and left him free to direct his remaining forces upon the important points of the theatre of operations. By uniting the Army of Reserve with Moreau's army, he could outnumber his adversary in Germany; or by uniting the Army of Reserve with a corps of Moreau's army, he could descend upon the rear of Melas, and decide in a single battle the fate of Italy.
By remaining on the defensive in Germany, Kray gave Bonaparte the opportunity of taking the offensive there. This allowed him to make use of the angular base of operations formed by eastern France and northern Switzerland. Bonaparte, however, could derive no advantage from the angular base except by taking the offensive; for should he simply defend the line of the Rhine, he would be obliged to occupy both the Swiss and French sides of the river. In other words, he would be obliged to divide his forces, to lengthen and weaken his line, thus giving his adversary the opportunity either to defeat the French forces in detail, or to force a passage across the river at some weak point. Furthermore, it was important that Bonaparte should take the offensive for other reasons than those already given; for should he once force the position of the Rhine and Black Forest, he would find no other great natural obstacles in his front as he descended the Danube towards the Austrian capital.
Because the strong position of the Rhine and Black Forest is a long distance from Austria; because the more direct route between France and Austria is through the valley of the Danube; because no great natural obstacles, forming strong defensive positions, lie across this route near the Austrian capital; and because a French victory in the valley of the Danube would probably give the French commander an opportunity to make such dispositions as should paralyze the operations of an Austrian army in Italy,—it follows that the main effort for supremacy between France and Austria should take place in the valley of the Danube. There Austria should take the offensive; there she should show her full strength; there she should make one mighty effort to decide her own or her adversary's fate. "It is in the valley of the Danube," says the Archduke Charles, "that the blows are to be struck which are decisive of the fate of France or Austria."
Austria did exactly the reverse of what she should have done. By taking the offensive in Italy, and by remaining on the defensive in Germany, she gave Bonaparte the opportunity to remain on the defensive in Italy and to take the offensive in Germany. She gave him the opportunity to carry out a plan of campaign which offered him the greatest results,—a plan which was perhaps, on the whole, one of the grandest strategic projects ever conceived by the mind of man.
"To invade a country," says Napoleon, "upon a double line of operations is a faulty combination." Though the Austrian plan was that Kray should remain on the defensive in Germany, while Melas took the offensive in Italy, yet both armies were, under certain circumstances, expected to invade France. Separated as they were by impassable obstacles, Bonaparte could leave a containing force to hold one in check, while he massed overwhelming numbers to crush the other. Thus by adopting a double line of operations, Austria gave Bonaparte the opportunity of bringing superior numbers against either Austrian army. As the first principle of war is to be stronger than the enemy at the vital point, it is always of the greatest importance that no plan of campaign be adopted which shall, at the very start, allow the enemy to bring superior numbers upon the battle-field. For the battle-field is the vital point.
The error of adopting a double line of operations might easily have been avoided by Austria. Had she left fifty thousand soldiers in Italy to hold Masséna in check, and concentrated one hundred and ninety thousand in Germany to act on the offensive, she would have confined her main efforts to the more important route between France and Austria, and would have had greater chances of success.