 Military planners in Paris understood that the northern Rhine Valley, the south-western German territories, and Switzerland were strategically important for the defense of the Republic. The Swiss passes commanded access to northern Italy; consequently, the army that held those passes could move troops to and from northern and southern theaters quickly. The river was a formidable barrier to what the French perceived as Austrian aggression, and the state that controlled its crossings controlled the river itself. Finally, control of the Upper Danube would allow France to move its troops from Italy to the North Sea, or any point in between, offering immense strategic value.
