"To enable the attack to be prosecuted it is clear that from this moment the hostile fire must be met by fire of greater power, its intensity and duration being dependent on the effect produced. Moreover, from this point forward movement will as a rule be contingent on the mutual fire support afforded to one another by neighbouring bodies, and on the effects produced by the covering fire brought to bear on the enemy's line wherever the ground admits of such action, by supports, reserves, and the troops specially told off for this purpose. Covering fire should be delivered so as to strike the enemy, disturb his aim, and compel him to seek shelter when the assailant is exposed or in difficulties. In such circumstances intensity of fire is of the first importance; but fire should be reserved when the assailants' progress is satisfactory, or when he is under cover."[A]
No one who has controlled the covering fire of infantry, even on manœuvres, will dispute the immense difficulty of timing the opening and ceasing of such a fire, with even a company, to coincide with the advance of the troops covered; while the necessity for observation of fire and its concentration on certain parts of the enemy's position make it still more difficult effectively to cover the advance of troops with rifle fire at long range.
That machine guns will be able to perform this duty far more effectively and easily than infantry is manifest from the nature of the fire
