_Machine Guns and Light Cannon._ The artillery can only give the second line a support which is often partial and not very effective; its action must be replaced at whatever cost by other means, such as machine guns for sweeping the hostile firing line and light cannon to instantly destroy the hostile machine guns. _Location of the Machine-Gun and Gun Crews during the Assault._—These detachments follow the last waves of the first line, and they therefore are not directly taken under fire and can profit by the indications of the fight of the first line and so be in a way to act effectively when the second line comes into action. _Machine Guns._—The machine gun is an element of attack and the most terrible arm of close fighting. However, it is employed in the attack only to man the positions taken or to support the infantry elements from a distance. This is nonsense: to give it such a rôle, one could never have trembled with rage and impotence at a few paces from the enemy, whom he could not get at. The machine gun should be pushed as far as possible in front of the halted line of fire. If it remains behind or abreast of the fighting line, its field of fire is generally blocked or masked by the slightest movement; in advance of the line, it will enable the infantry line to advance for some time under the cover of its fire; it is the tooth of the attack. It can move forward, its crew of a few men can creep along the smallest pathway, and a shell hole is sufficient for its shelter; in the skirmish chain a whole ditch is necessary. Will it lack ammunition, having only the boxes that the gun crew carries sometimes incomplete? No, for it has only to fire on rare occasions, for example, at the moment of assault. If it is taken, what does that matter—we will take ten from the enemy. The problem would be much simplified _with a few automatic rifles_. _Light Cannon._—We have spoken of the rôle of light cannon in the paragraph relating to the destruction of machine guns. _Instruction of Units of the Second Line._ This instruction proposes to create the reflex of immediately attacking all resistance that appears and of developing presence of mind by inventing sudden incidents requiring the taking of a rapid decision. In a word, to add a spirit of prompt decision in the troops of the second line to the irresistible _élan_ which one tries to develop in all assaulting troops. The troops of the second line when facing a resistance should have only one idea: to assault as soon as possible and for that purpose to try to bring about the two following conditions: _To create a sort of parallel of departure at assaulting distance_; _To obtain superiority of fire by all means at their disposal._ We will study by means of examples the two preceding cases cited. Troops of the second line should know them by heart, because all cases resemble them more or less.