On the other hand, the three French armies were so situated that they could support one another. With Moreau's army on the Rhine, Masséna's along the Apennines, and the Army of Reserve between them near Lake Geneva, Bonaparte could move the last along the roads of eastern France to re-enforce either of the others as circumstances might require. In this way Bonaparte could re-enforce Masséna with the Army of Reserve, which would increase the Army of Italy to eighty thousand combatants. Or, should Masséna be driven back across the Var into France, Bonaparte could leave Moreau on the defensive along the Rhine with a part of his army, withdraw the remainder, unite it with the Army of Reserve, and with these combined forces added to the remnants of Masséna's army, destroy Melas in the south of France.
Had the Austrian armies succeeded in invading France simultaneously, Bonaparte would have detached a containing force[3] against one army, and then have massed his remaining forces against the other. By repeating this manoeuvre, first against one army and then against the other, he would have attempted to defeat both. In this case, the Austrian armies would enter France from different directions; one from the east, the other from the southeast, separated by Switzerland and the French Alps; and since the French armies, even while falling back, would still be between the Austrian armies, Bonaparte would, from his central position, have the advantage of interior lines, and could rapidly combine his forces against his adversaries in succession.
How well he would have succeeded in this manoeuvre can best be judged by what he accomplished by similar manoeuvres.
In the Italian campaign of 1796-97, when the Austrians advanced against Bonaparte on both sides of Lake Garda, he united his forces at the foot of the lake; and, by throwing a strong force against one and then against the other of the advancing armies, defeated both in succession before they could unite. In these manoeuvres, with a total force of forty-five thousand soldiers, he defeated seventy-two thousand Austrians.
In the campaigns of Arcole and Rivoli, the Austrians likewise advanced with divided forces. In the former, forty thousand Frenchmen opposed seventy thousand Austrians; in the latter, forty-four thousand Frenchmen opposed sixty-five thousand Austrians. By skilful combinations, similar to those just described, Bonaparte defeated the Austrian armies in both campaigns.