"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. Had this plan been followed, Bonaparte could not, by any strategical combination, have outnumbered the Austrians in Germany. Since it was necessary that the Army of Italy should remain along the Apennines and Maritime Alps to prevent the invasion of France on that side, the maximum strength which Bonaparte could direct against the Austrians in Germany was Moreau's army of one hundred and thirty thousand and the Army of Reserve, forty thousand strong. In other words, Bonaparte could bring only one hundred and seventy thousand Frenchmen to oppose one hundred and ninety thousand Austrians.