Whatever of technical value the other reports may have,--and they are, we doubt not, excellent,--McClellan's is the only one of popular interest, the only one of rounded proportions and general importance; and if it also contain much addressed to the professional soldier, it must be remembered that the country is now being educated up to the intelligent perusal of such books. Travelling in all the principal countries of Europe,--Montesquieu's assertion is now verified, that "only great nations can have large armies,"--the commission met everywhere proper facilities for observation. McClellan made full notes upon the spot, procured all the books of Tactics, Regulations, Military Laws, etc., and provided himself with such models of arms, equipments, saddles, bridles, tents, etc., as were easily transported. Operations of a difficult and laborious character, such as carrying horses on shipboard, are fully demonstrated with diagrams. Marches, manoeuvres, detachments, battles, are fully disclosed. Such investigations, when the French, Italian, or German language was the medium, were comparatively easy; but in order to give a proper comparative view, he was obliged also to study Russian, which he did successfully; by this means he has given us a masterly summary of the Russian system, with its immense battalions, its thousands of military schools, and its Cossack skirmishers, of wonderful endurance and formidable fierceness. The volume is a complete description in detail of the principal armies, and of wider scope than would be expected; for, while the author has been very full upon the special topics assigned him, which did not include the duties of Engineers and Engineer Troops, it is easy to see everywhere that these latter would intrude themselves with the siren charms of a first love, and nothing but the record could dissolve the spell. Indeed, he urgently recommends to the Government the organization of Engineer troops, specifying their equipments, points of instruction, and duties. In this department, his description of Military Bridges is of great value. Incident to the faithful descriptions contained in the Report, and by far the most valuable feature of the work, we would specify his comments upon all that he saw. They are manly and bold, but _raisonnés_ and just. They give token of that originality of thought which we call genius. The opening chapter on the Crimean War is the only fair critique of that gallant, but mismanaged campaign we remember to have seen. The author's object is to exhibit the movements of both Allies and Russians "As truth will paint them, and as bards will not." When MeClellan's work first appeared, the "Athenaeum" took up spear and shield; but, _selon conseil_, McClellan declined to reply, and the champion fought the air, without injuring the record.