Those points the possession of which would give the control of the junction of several valleys and of the center of the chief lines of communication in a country are also decisive geographic points. For instance, Lyons is an important strategic point, because it controls the valleys of the Rhone and Saône, and is at the center of communications between France and Italy and between the South and East; but it would not be a decisive point unless well fortified or possessing an extended camp with têtes de pont. Leipsic is most certainly a strategic point, inasmuch as it is at the junction of all the communications of Northern Germany. Were it fortified and did it occupy both banks of the river, it would be almost the key of the country,—if a country has a key, or if this expression means more than a decisive point.
All capitals are strategic points, for the double reason that they are not only centers of communications, but also the seats of power and government.
In mountainous countries there are defiles which are the only routes of exit practicable for an army; and these may be decisive in reference to any enterprise in this country. It is well known how great was the importance of the defile of Bard, protected by a single small fort, in 1800.
The second kind of decisive points are accidental points of maneuver, which result from the positions of the troops on both sides.
When Mack was at Ulm, in 1805, awaiting the approach of the Russian army through Moravia, the decisive point in an attack upon him was Donauwerth or the Lower Lech; for if his adversaries gained it before him he was cut off from his line of retreat, and also from the army intended to support him. On the contrary, Kray, who, in 1800, was in the same position, expected no aid from Bohemia, but rather from the Tyrol and from the army of Mélas in Italy: hence the decisive point of attack upon him was not Donauwerth, but on the opposite side, by