On the defense the man’s protection is much better for he will generally have cover of some kind, but he has also a serious disadvantage, the line remains fixed, the hostile artillery soon locates it, gets its exact range and can place its own fire where it will do the most good. This is a decided offset to the defenders’ diminished vulnerability. The use of high explosive shells by their moral as well as physical effect weakens any advantage the defense might have as concerns artillery fire. [Sidenote: Artillery targets] To determine the relative vulnerability of different infantry formations let us apply to them the target made by a bursting shrapnel. A line of skirmishers at the normal interval extending across this beaten zone would have 19 or 20 men inside its extreme limits; if in squad columns there would be 2 squads at least and generally 3 squads or 24 men and the target, being much deeper, would give the artillery a better chance as it is easier to get direction correctly than the point of burst. In platoon columns there can be but one platoon in the same burst if fire comes from the front, and platoons are 4 squads strong, but the whole platoon may be within it. If, however, the direction of the artillery fire be very oblique, and the platoons are on a line, more than one platoon may be caught by a single burst but not all of any one column. In successive thin lines, if the advance be made by one man from a squad, and the fuze and direction be just right, there may be 2 men in the cone of dispersion, which is to say that, in that formation, the artillery has about one chance in forty of wounding a man. If the advance be by one man from each platoon the artillery’s chance, provided range and fuze are correct, is one in two that one man will be within the cone of dispersion of a given shrapnel and, if in there, there is one chance in 80 of his being hit; in other words, the artillery has one chance in 160 of getting one man and no possibility of getting two. Such a target will hardly draw artillery fire. An infantry battalion in column of squads well closed up can nearly all be covered by the burst of a shrapnel. Such a target would likely draw many shots as would a company in this formation. [Sidenote: The advance under artillery fire] We can only win in the attack if our infantry can advance to the hostile position. We must get there, and as soon as practicable and with the least loss of life. We can not afford to lose too many in the advance or we shall be too weak at the end to drive the enemy from his position.