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. THE NATION-IN-ARMS The nation-in-arms as the common foundation of all armies (except our own), brought up by railways, vastly increases the numbers in a modern battle from what they were in Clausewitz's day. Compare Austerlitz, Dresden, Leipzig and Waterloo, with Liao-yang and Mukden. It should be so with us also, for as General von der Goltz says in "The Conduct of War": "The BEST military organization is that which renders available ALL the intellectual and material resources of the country in event of war. _A State is not justified in trying to defend itself with only a portion of its strength, when the existence of the whole is at stake._" In Great Britain the difference which the introduction of this nation-in-arms principle has made in our military strength compared with that of our future opponents, a difference relatively FAR GREATER AGAINST US than it was in Napoleon's and Clausewitz's day, is as yet hardly realized by the people, or by our statesmen. People forget the wastage of war, and the necessity for a constant flow of troops to repair that wastage. As Von der Goltz puts it: "It is characteristic of the strategical offensive that the foremost body of troops of an army, the portion which fights the battles, amounts to only a comparatively small fraction, frequently only _a quarter or even one-eighth_, of the total fighting strength employed, whilst the fate of the whole army throughout depends upon the success or failure of this fraction. _Attacking armies melt away like snow in the spring._" To condense his remarks: "In spite of the most admirable discipline, the Prussian Guard Corps lost 5000 to 6000 men in the marches between the attack on St. Privat and the battle of Sedan." "Napoleon crossed the Niemen in 1812 with 442,000 men, but reached Moscow only three months later with only 95,000." In the spring of 1810, the French crossed the Pyrenees with 400,000 men, but still Marshal Massena in the end only brought 45,000 men up to the lines of Torres Vedras, near Lisbon, where the decision lay. Again, in 1829, the Russians put 160,000 men in the field, but had barely 20,000 left when, at Adrianople, a skilfully concluded peace saved them before their weakness became apparent and a reaction set in. In 1878 the Russians led 460,000 across the Danube, but they only brought 100,000 men--of whom only 43,000 were effective, the rest being sick--to the gates of