As we penetrate deeper and further from our own country into the enemy's, and as a small raiding party can demolish the railway line so as to stop all traffic for days or weeks, it becomes far more necessary than it ever was in Clausewitz's day to guard our communications. And armies become more and more sensitive to any attack upon their communications. Also "such a line cannot easily be changed, and consequently those celebrated changes of the line of communication in an enemy's country which Napoleon himself, on some occasion, declared to be the ablest manoeuvre in the art of war, could scarcely be carried out any more" (V. Caemmerer). Also concentration by means of several railways demands a broad strategic front, which produces that separation of corps or armies which prepares the way for strategical envelopment, and so on. General von der Goltz, in his "Conduct of War," says: "The more recent treatises on the conduct of war on a large scale are principally taken up with the mobilization and strategical concentration of armies, a department of strategy which only began to play an important part in modern times. It is the result of a dense net-work of railways in Western Europe which has rendered it possible to mass large bodies of troops in a surprisingly brief time. Each Power tries to outdo its neighbours in this respect, ... which gives an opportunity to the strategical specialist to show off his brilliant qualities.... Consequently it is now frequently assumed that the whole conduct of war is comprised in this one section of it." This over-estimate is of course an error, which, however, requires to be pointed out. TELEGRAPHS The telegraph has very greatly reduced the danger of separation. The great advantage of the inner line in the day of Napoleon and of Clausewitz was that separated forces could only communicate by mounted messengers, so if the enemy got between them they could not communicate at all, nor act in concert. This the telegraph has completely altered, for as the field telegraph can now be laid as quickly as an army can advance, the most widely separated bodies of troops can every day arrange combined operations by telegraph through, if necessary, a point one hundred or four hundred miles in rear. So that to-day the chief advantage of the inner line has gone, while its chief disadvantage, the possibility of being surrounded, remains. MAPS We now possess complete detailed Ordnance maps of every country in Europe, kept up to date by the latest alterations, whereas in the days of Clausewitz maps were of the very roughest character, and quite unreliable in comparison. IMPROVED ARMS