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
Smokeless powder, quick-firing and long-ranging artillery and rifles, the infantry field of effective fire being ten times, the artillery five times what it was in Clausewitz's time, have all to be borne in mind when reading the tactical part of his writings. In consequence, also, cover and the tactical use of ground are of far greater importance now than then, etc., etc., etc.
Aviation
The recent wonderful developments in aviation will obviously almost revolutionize "Information in War." To what extent, it is as yet impossible to say. Each year will teach us more.