Skirmishers, by the looseness of their formation, are dangerously exposed to charges from small parties of the enemy’s light cavalry; and in districts destitute of continuous fences, but abounding in hollows, isolated patches of wood, or other features convenient for concealment, such attacks may burst forth with most confusing suddenness. Except in ground absolutely impracticable for cavalry, skirmishers must move in constant expectation of them. The eye of the officer should be accustomed to recognise habitually those frequently occurring posts of defence against cavalry, copses, walls, hedges, ditches, &c., which are preferable to small squares; and the minds of men should be well prepared by previous instruction _and explanation_, to recollect, in an instant, in what their strength in such cases consists, and to be undaunted in it. Against great charges of cavalry, large squares are unquestionably the safest and most efficient; but, in opposition to the small dashes which occur in skirmishing, large squares are often impracticable, and small ones more advisable, as being more rapidly formed and broken up. Squares have a moral strength in proportion to the mutual acquaintance of the men and officers who compose them. Men of the same company stand better together than those of mixed companies, and men of the same regiment better than those of different corps. However, as in the field thorough mixtures do occur, and as they, if observed, are likely above all other things to bring on charges from the enemy’s cavalry, squares of mixed masses should, in instruction, at times be practised. It is not necessary to describe the different modes by which, on the drill field, men may be thrown into confusion. When this state of things has been brought about, mixed, irregular, rallying squares can be formed by adding the “double quick” to the ordinary sounds for squares against cavalry.[13] The “double quick” is required to mark the necessity for instantaneous irregular masses, in contradistinction to the more regular squares, _which on the drill field skirmishers should always endeavour to form, unless at the time otherwise ordered_. It cannot be too constantly upheld as a permanent principle that, even in skirmishing, _order is the rule and irregularity the exception_. On the signal “double quick” in immediate succession to the sounds established for the formation of squares,[14] officers, exercising most actively their intelligence, in proper numbers and at proper distances, hold up their swords or caps, and the men rush round them into masses of defence without any regard to company or other distinctions. These mixed squares, as well as all others, may “commence firing”—“cease firing”—“advance”—“retire”—“take ground to a flank,”—or “close” to any particular square, by order, or by the simple sounds for these movements. The “close” may be important to form a large square from several small ones, the cavalry still hovering near.