The importance of envelopment, both strategic envelopment and tactical envelopment, of course remains very great. Clausewitz says[6]: "A complete victory requires an enveloping attack on a battle with an oblique front, for these two forms always give the result a decisive character." Moltke furnished proof of this at Königgrätz, Metz, and Sedan. Schlieffen, who made it his chief object to keep the desire for the annihilation of the enemy alive in the German army through the long period of peace, developed in his "Cannae" the conditions for a battle of annihilation on classical lines. Even if, as the World War has shown, his doctrines frequently have to be modified, when they are applied to conditions of very large scale, none the less this War too has furnished instances where the envelopment of a whole host might have been effected and would have had very far-reaching consequences. Such an opportunity was presented to our opponents on the Western front after the Battle of the Marne. By making use of their convenient and efficient railway network and their numerous columns of motor wagons, they might have hurled at the proper moment powerful forces against the right flank of the German army and thereby prevented us from establishing our positions on the Aisne and to the west of the Belgian frontier. Since, however, they had not achieved a tactical success at the Marne at all, they lacked the strength and the capacity for such an undertaking. They pressed their attack only in a frontal direction. The German forces at once resumed in part an offensive attitude, and by this means arrested the progress of the enemy forces opposed to them. They strengthened the right wing of their army, and were always able to oppose adequate forces to the striking movement of the French pursuing army when the latter at length (but too late) set itself in motion, and this even though the railway network in Belgium and North France had not yet been restored to anything like full efficiency.