This geometrical alteration could only be completely carried out by tactics, and by it only through the file-march as it is called, which, with great masses, is impossible. Far less is it possible for strategy to do it. The parts which changed their geometrical relation in the old order of battle were only the centre and wings; in the new they are the divisions of the first rank corps, divisions, or even brigades, according to the organisation of the army. Now, the consequences above deduced from the new order of battle have an influence here also, for as it is no longer so necessary, as formerly, that the whole army should be assembled before action commences, therefore the greater care is taken that those troops which march together form one whole (a unit). If two divisions were so placed that one formed the reserve to the other, and that they were to advance against the enemy upon two roads, no one would think of sending a portion of each division by each of the roads, but a road would at once be assigned to each division; they would therefore march side by side, and each general of division would be left to provide a reserve for himself in case of a combat. Unity of command is much more important than the original geometrical relation; if the divisions reach their new position without a combat, they can resume their previous relations. Much less if two divisions, standing together, are to make a _parallel_ (flank) march upon two roads should we think of placing the second line or reserve of each division on the rear road; instead of that, we should allot to each of the divisions one of the roads, and therefore during the march consider one division as forming the reserve to the other. If an army in four divisions, of which three form the front line and the fourth the reserve, is to march against the enemy in that order, then it is natural to assign a road to each of the divisions in front, and cause the reserve to follow the centre. If there are not three roads at a suitable distance apart, then we need not hesitate at once to march upon two roads, as no serious inconvenience can arise from so doing. It is the same in the opposite case, the flank march.