Now Mr. Nickerson has done exactly that right thing for the Albigensian War. He clearly divides the struggle into its _military_ episodes; the first great rush; the long struggle of de Montfort; the curious but inevitable fruit of the whole business after de Montfort’s death in the lapse of the South to the crown of France, that is to the North. In this connection one cannot praise too highly the simple and clear fashion in which the author has presented to the reader the real nature of mediæval warfare. There are two points to be established in which, I think, he has been permanently successful. First, in making the reader understand the narrow limits of time to which any effective work on a large scale by a powerful army was then confined. Secondly, the contrast between the feudal forces which were, as it were, normal to the times, and those supplementary mercenary forces, which, though they were not regarded by the time as normal, were the real backbone of all continuous military effort in the West. It is an idea which one might develop in many epochs of military history besides the Middle Ages. Over and over again a particular form of recruitment is regarded as normal and after use for some generations begins from causes inherent in itself to yield insufficient results; whereupon a supplementary form of recruitment, which for long continues to be regarded as exceptional, becomes, as the close observer may discover, the essential of the new fighting force, e.g., the Auxiliaries and the Legions after, say 180, and especially after 312. It was one of the advantages of the English, by the way, in the later Middle Ages that the difficulty of transporting large feudal forces over the sea led to an early development of their mercenary forces and produced the highly trained professional bowmen who are the mark of the Hundred Years War. Mr. Nickerson is also right in saying how considerable was the degree of military organization in the early thirteenth century. Too often in military history anything earlier than the seventeenth century or the middle of the sixteenth is treated unscientifically by the writer, who seems to imagine that if he gets far enough back he can treat armies as herds moving about at random. The truth is of course that no great body of men ever so moved or could be moved without a high degree of organization, and that when you are dealing with the _rapid movement_ of a very large body the organization must be nearly as detailed as it is to-day. There is a certain minimum of organization below which you cannot fall without breaking down, when it is a case of great bodies moving quickly; and that minimum is so high that it does not vary very much between the very first epochs of recorded history and the latest.