Of geographical advantages attaching to the position of Russia only one can be discovered, and it consists in the immense extent and unity of the Russian Empire. This permitted operations upon a western front from the Baltic to the Carpathians, or rather to the Roumanian border, which vast line could never be firmly held against them by the enemy when once the Russians had trained and equipped a superior number of men. The German forces were sufficient, as events proved, long to maintain a strict cordon upon the shorter front between the Swiss frontiers and the sea, but upon the other side of the great field, between the Baltic and the Carpathians, they could never hope to establish one continued wall of resistance. (2) THE OPPOSING STRENGTHS. When nations go to war their probable fortunes, other things being equal, are to be measured in numbers. Other things being equal, the numbers one party can bring against the other in men, coupled with the numbers of weapons, munitions, and other material, will decide the issue. But in European civilization other things are more or less equal. Civilian historians are fond of explaining military results in many other ways, particularly in terms of moral values that will flatter the reader. But a military history, however elementary, is compelled to recognize the truth that normally modern war in Europe has followed the course of numbers. Among the very first, therefore, of the tasks set us in examining the great struggle is a general appreciation of the numbers that were about to meet in battle, and of their respective preparation in material. More than the most general numbers--more than brief, round statements--I shall not attempt. I shall not do more than state upon such grounds as I can discover proportions in the terms of single units--as, to say that one nation stood to another in its immediate armed men as eight to five, or as two to twenty. Neither shall I give positive numbers in less than the large fractions of a million. But, even with such large outlines alone before one, the task is extraordinarily difficult. It will almost certainly be found, when full details are available after the war, that the most careful estimates have been grievously erroneous in some particular. Almost every statement of fact in this department can be reasonably challenged, and the evidence upon matters which in civilian life are amply recorded and easily ascertainable is, in this department, everywhere purposely confused or falsified.