As a consequence of the increased liability to interruption of these communications, and also of the far more serious confusion to which any such interruption can give rise, it has become far more difficult than in the past to execute offensive flanking operations, changes of front, or counter-attacks, all of which are movements which the practical strategist must bear in mind. On paper and on the map such undertakings appear to present no more elements of friction than formerly, but on the ground itself those who have once seen masses of several corps all huddled together know that things are very different. All such movements nowadays are tied to the railway-lines, and these, again, are congested by the flow of food and ammunition, which must at all costs be maintained. Fresh units also of troops may be coming up to the front, whose arrival is of the last importance in the plans of the generalissimo, and a single broken viaduct may throw confusion into the whole design. In a densely-populated and fruitful district the resulting failure of supply may be endured, but it is very different when in a poverty-stricken district the supply of a whole Army depends on perhaps a single line of railway. Thus the Cavalry sees itself confronted by a task in the solution of which it can achieve results of _decisive importance_ in a new direction, for the following reasons: The relative importance of the Arm during actual operations having been materially increased, the period of concentration preceding actual collision (notwithstanding the fact that the actual effectiveness of Cavalry in the face of modern firearms has been decreased) offers opportunities which under certain conditions promise higher results than formerly. If every delay in the march which may be caused by the action of Cavalry against the flanking lines of advance of an Army concentrating for battle is detrimental, how much greater would be the disorganization resulting from similar operations after defeat! Very rarely in such a case would it be possible to retire eccentrically by the same roads which were used for advance. The beaten troops generally drift back quite involuntarily in the direction into which they have been compelled by the results of the tactical decision. The wider the original front, the greater the masses of the troops concerned (which are now not only in a demoralized condition, but are compelled, under pressure of pursuit, to change their communications into new directions, and for this purpose to disentangle the columns drawn in for the concentration) and the greater the certainty that conditions must arise which will give to an active Cavalry an even richer opportunity of harvest than was formerly open to them.