(Figure 25.) The combined order in columns on the centre and one extremity at the same time, is better suited than either of the preceding for attacking a strong contiguous line. Napoleon employed this order at Wagram, Ligny, Bautzen, Borodino, and Waterloo. It is impossible to lay down, as a general rule, which of these orders of battle should be employed, or that either should be exclusively followed throughout the whole battle. The question must be decided by the general himself on the ground, where all the circumstances may be duly weighed. An order well suited to one position might be the worst possible in another. Tactics is in this respect the very reverse of strategy--the latter being subject to more rigid and invariable rules. But whatever the plan adopted by the attacking force, it should seek to dislodge the enemy, either by piercing or turning his line. If it can conceal its real intentions, and deceive him respecting the true point of attack, success will be more certain and decisive. A turning manoeuvre may frequently be employed with advantage at the same time with the main attack on the line. The operations of Davoust at Wagram, and Richepanse at Hohenlinden, are good examples under this head. The manoeuvre is, however, a difficult one, and unless executed with skill, may lead to disasters like the turning manoeuvres of the Austrians at Rivoli and Austerlitz, and of the French under Jourdan at Stackach, and under Marmont at Salamanca. We will now discuss the particular manner of arranging the troops on the line of battle, or the manner of employing each arm, without entering, however, much into the detailed tactics of formation and instruction. We shall begin with _infantry_, as the most important arm on the battle-field. There are four different ways of forming infantry for battle: 1st, as tirailleurs, or light troops; 2d, in deployed lines; 3d, in lines of battalions, ployed on the central division of each battalion, or formed in squares; 4th, in deep masses. These different modes of formation are reduced to four separate systems: 1st, the thin formation of two deployed lines; 2d, a line of battalions in columns of attack on the centre, or in squares by battalions; 3d, a combination of these two, or the first line deployed, and the second in columns of attack; and 4th, the deep formation of heavy columns of several battalions. The tirailleurs are merely accessories to the main forces, and are employed to fill up intervals, to protect the march of the columns, to annoy the enemy, and to manoeuvre on the flanks.