This curtain of fire continues for hours; it varies in direction now and then, but never in intensity. There is a controlling force over this tremendous bombardment. To my mind the most important man on the battle-field is he who holds the ordering of the bombardment--the observation officer. He must know everything, see everything, but must never be seen. During a heavy bombardment he works in conjunction with another observation officer. They are hidden away in any old place; it may be a ruined chimney, it may be a tree which is still left standing, or it may be in some hastily built up haystack. He controls the entire artillery in action on his special front, and he holds the lives of thousands of men in the hollow of his hand. One tiniest miscalculation and hundreds of us pay the price. He is cool, imperturbable, calculating, ready in any emergency, good-tempered, deliberate and yet with the power to act instantly. At times he has command over a magnificent number of invectives! As the minutes pass and the day lightens we smoke a fag every five minutes, every three minutes. The trench is filled with the blue gray smoke of thousands of cigarettes, lighted, puffed once, thrown away. It soothes our nerves. It gives us something to do with our hands. It takes our mind off the impending clash. If we make an attack in broad daylight, which is seldom done except under a special emergency, the only command to charge will be the click, click, click of bayonets going into place all along the line. But charges are mostly made at gray-dawn, when bayonets are already fixed. Suddenly, away down the line we catch sight of one of our men climbing over the parapet. Then trench ladders are fixed, and in a twinkling every man of us is over the top with: "The best o' luck--and give 'em hell!" We crawl out over the open. We reach our own barbed wire entanglements. We creep through them, round them, and out to No Man's Land. We are in it now for good and all. The enemy is now concentrating his fire on our reserves. He knows that we have not had sufficient men in the front line trench to be of great effect. He knows that we can not fit them in there. He knows that the moment we have cleared the top of the parapet hundreds of men have poured from the communication trenches into our places. He knows that for miles back men are massed as thick as they can stand in the reserve trenches. His object is to destroy our reserves and not the immediate trench in front of him.