At this juncture let me run over the development of barrage fire as military critics look upon and explain it.

Petain, the great French general, has given expression to one of the outstanding facts of the present war. He says, "The artillery conquers, the infantry occupies." This, in a few words, is the explanation of that new method of attack by "barrage" or, as the English call it, "curtain fire."

This system of attacking the enemy is a new one and has proven most effective for the Allies. In a nutshell, it creates what might be called a danger zone, or, better still, a death zone, just in front of the advancing soldiers. As the soldiers move on ahead the barrage moves on, or it may be more proper to say that the soldiers move just as slowly as the curtain of fire moves, for if they do not, fatal consequences follow. If they should go too fast they would run into the barrage and would be killed by their own artillery, which is in the rear of the trenches. Occasionally a soldier becomes too enthusiastic and goes too fast for the barrage, and then disaster follows. Accuracy, in time and in range, is the one thing which must be most strictly observed by the men who are conducting the barrage hundreds of yards back of the line.

These men project a hail of shells over the heads of their own infantry and across a thin strip of land parallel to the enemy's trench and directed in the first place at his barbed-wire defenses. This line or belt of bursting shells must be so fierce and continuous as to make it impossible for any man to go through it, or at least so perilous and costly to life that no one in his proper senses would try the hazardous experiment. It requires a rapid firing gun for this kind of warfare, and as armies have not had such guns heretofore, of course, the barrage fire was unknown. It is one of the new things that have been evolved during this war. The French soixante-quinze, or "seventy-five millimeter," has been the marvel in gun making which has made this curtain fire possible. It is a gun which shoots very rapidly, which does not displace itself each time it shoots, and which is able to discharge an average of twenty-five three-inch shells every minute without greatly heating up. No gun was ever invented before which could accomplish such a feat.

The older four-inch gun of the French Army, which the seventy-five displaced, could never have shown the efficiency in this direction that the soixante-quinze demonstrates. In the first place its rate of shooting was much too slow, but even if it had been a great deal faster a continuous accuracy was impossible. When it was first aimed its fire could be carefully controlled, but the trouble with it was it threw itself out of place every time it shot. The recoil from such guns is very considerable and the older gun made no provision for it, consequently it had to be aimed all over again every time it was fired because the rebound caused it to dig into the earth and change its entire position. The new soixante-quinze makes careful provision for this factor of recoil and is fitted up like a Ford car with shock absorbers, so that it is ready for the second shot as soon as the first is fired, and for the third as soon as the second is fired. It maintains a fixed position, accelerating very greatly the speed at which it can be fired at any given target. The old four-inch gun fell down just here. The result was that its highest rate of speed was only a quarter of that which could be attained when a field piece was invented, absorbing its recoil and thus leaving its position unchanged. The only limit to the speed of the new gun, therefore, is the rate at which it can be loaded and the degree of temperature it can stand without exploding shells prematurely, but even this latter danger is provided for in this gun, thus keeping it to the minimum. The only elements that prevent absolute accuracy today are slight differences in the shells or perhaps a change of wind, which are, however, practically negligible factors.

Formerly, in the use of the other gun there was the personal variation of the man who aimed the gun quickly, after each shot had displaced or disarranged it, and the other man who assisted him. Each new aiming and shooting of the piece required an absolutely distinct series of movements and thus for every shot there was that much more possibility of error on account of the imperfect coordinating of the two men engaged. In this connection let me say that the curtain fire, which was evolved by the modern quick firing seventy-five, was very soon discovered and quickly adopted and utilized by Germany also.

When first used the purpose of curtain fire was simply to guard or make possible the forward movement of the infantry and was kept well ahead of them, usually one or two hundred yards. It was also uniform all along the line as far as it extended; that is, if it moved ahead a hundred feet at one point it moved the same amount at every other point. It is a ticklish thing at first for men to advance upon the enemy's trenches with their own artillery booming away at their rear and shooting right over their own heads. But the trenches are seldom parallel. Often the country is rough and whereas the enemy may be dug in a hundred yards away at one point, it may be that fifty rods farther down the lines, the trenches are three hundred yards apart. In the main we speak of the lines being parallel, but as a matter of fact they very seldom are so.

During the early days of the war if one of the opponents were going to make an attack he hammered the enemy's position with heavy guns which were concealed or camouflaged perhaps five miles behind the front line trenches. The bombardment lasted until it was assumed most of the enemy's soldiers had taken refuge in the dugouts and were so disorganized that they could not effectively resist. Besides this his trenches would be so battered that the chances of success for the well-planned assault would be the best. The time must be accurately arranged previously. All lieutenants and captains who directed the barrage must keep exact time and have watches timed to the second. My own brother, Brenton, is now a lieutenant of artillery and I had the pleasure of presenting him with a beautiful stop-watch before he went into action.

At the given signal the barrage raised and the doughboys went over the top, hustled down the lanes which had been previously cut in their own barbed wire by the wiring party, made their way across No Man's Land, stooping low as they went, dropping flat to the ground every few yards, and trying to get to the trenches of the enemy before they could be stopped.

But the machine guns of the enemy were found to be too formidable and destructive, and as a result of this experience they learned to use the light artillery which could continue its fire even while the attacking party were moving on, advancing as they advanced. The lighter field pieces were placed within a few hundred yards in the rear of the trenches and used to blind the Germans from protecting themselves, as well as to cover the advancing troops until they took the trench. Then the curtain fire was thrown still farther back behind the German line.

This process plainly was a very delicate one, even in its beginning. It seemed a little nervy to order soldiers to advance while above their heads hissed and barked their own gunners' shells. Sometimes these would burst before they got to the curtain line and casualties would inevitably result. It was rather ticklish business for the men to charge forward even if they were a couple of hundred yards behind such a hail of steel.

Soon, however, another improvement was put into effect and that was to shorten the barrage to sixty yards, letting the soldiers advance with the exploding shells nearer and nearer to their own bodies. Of course, there was great advantage in this, as the closer the troops were to the curtain fire ahead, the better they were protected and the shorter was the time after the curtain was lifted until the troops occupied the trench. Cutting this time down to the minimum made it so much harder for the Germans to emerge from their hiding and resist the oncoming troops. The science of this was at last so well worked out that a gap of less than forty yards lay between the curtain and the troops and sometimes only thirty yards which could be covered in a couple of seconds after the barrage was lifted. Time, of course, is the chief element in the endeavor to get the bulge on the other fellow.

Finally the British worked out what they call the "creeping barrage." This takes into account the fact that the trenches are never exactly straight and parallel. But here the camera came to the aid of the Allies and it told them just how much deviation from the parallel there was. From these photographs the relative positions of the trenches at any given point were plotted out accurately, showing the irregular shape of No Man's Land and the variation of its width at all the different places. The Allies then dug identical trenches in the rear and practiced on them. This changed the method of curtain fire from "regular" to "creeping." From that time the barrage started in a line which first followed the shape of our own fire trench, but as it moved forward the configuration was altered and it swayed and wriggled like a snake gradually taking the shape of the enemy's trench. Plainly, it required much deeper skill to employ this method, but its advantages were great. Instead of all the gunners shooting in unison at a single command, each one had a different job to perform in order to make the barrage conform with the angle which the trenches made. This is now the general method and has been brought up to a marvelous degree of accuracy as well as speed.

At practically the same time the creeping barrage was conceived, another idea which has also been extremely useful was developed. This was the second curtain of fire to be thrown in the rear of the enemy's trenches to cut off his retreat and to prevent the coming up of reinforcements. The first curtain covered your advance and hindered his resistance, and the second one beyond him kept new forces from coming to his aid with food, munitions, and information.

The method which is used almost universally in attacking today, then, is this.

Big guns "prepare" the way by hammering the trenches of the enemy and simultaneously driving him to the dugouts and bashing in the trenches which shelter him. Your doughboys then go "over the top" and advance, covered by the curtain fire, at first conforming in shape to their own trenches, and little by little wriggling into the form of the enemy's trenches as it comes nearer to them. Closely following the moving barrage is your infantry. Then another barrage in the enemy's rear is cutting him off from reinforcements and after a time the trench is captured and perhaps many prisoners taken. It is not hard to understand from this modern method of attack what the French general meant when he said, "The artillery conquers, the infantry occupies."

Barraging on the field today is much the same as running a great ocean liner. The man who sees is not the man who does! The lookout or observer has nothing to do with the actual control of the vessel. The battery on the field is pulled up into position by horses, then lined up for action and the horses are hurried back to a safe place. The lieutenant directs the fire and the gunners do the firing, but no one sees his target or his results. Just behind them, a telephone operator receives the messages, sitting perhaps, in a shell hole or a dugout. The battery commander is the man who really bosses the whole job from his observation post. He is well named because he really commands the battery, though from a position perhaps miles in front of the battery. The lieutenant is always listening as the telephone operator is getting his instructions from the commander at the front. In the first place the lieutenant learns roughly the direction in which to shoot, but soon he gets more detailed direction before firing his first shot, which is in reality an experiment. Standing a short distance behind the battery, he plainly sees every gun. Then he shouts, "Ready!" When the command to fire comes over the telephone he issues a signal. The man at the first gun raises his hand, five seconds are counted, and as he drops his hand the gun is fired. Gun number two does the same and so on down the line. The gunner cannot see and does not know anything about the result. The man at the telephone calls out, "Battery has fired."

The only man in all this operation who gives orders and sees results is the battery commander. Usually he can see the target clearly. Sometimes, however, when this is not possible the balloon and the airplane have to do it for him. The battery commander with the telephone operator in his rear knows exactly the way the guns are pointed and the distance to be covered. He can estimate quickly and figure up the necessary corrections, and this message may go back to the battery, "One hundred yards over and fifty yards to the right." The sergeants then again revolve their control wheels.

The Good Book says, "A great ship is turned about by a very small helm." And so does a great gun respond very quickly to the most delicate touch of the wheel. The gauge is very fine and accurate and a hair's difference there means rods of difference where the shell falls. If the initial shot went a hundred yards over, perhaps the second goes one hundred yards too short. The direction is correct. Again in obedience to a message from the commander the little wheels move, and the elevation of the gun is corrected. The third shell, perhaps, goes over fifty yards and the fourth fifty under. Very well, the range is somewhere between those last two shots. "Give 'em hell. Salvo!" shouts the lieutenant: salvo meaning the firing of all the guns at one time.

Sometimes it is not practical to have an observation post located so as to allow the commander of the battery to see the result and direct the shell fire. In this case he has a balloon which is fastened to the earth by a cable and sent up behind the lines and out of range of the Germans. At best it is an uncomfortable position to be in; hung up in a basket maybe four thousand feet above terra firma, with German fliers hovering about and trying to blow you into eternity. It's not soothing to the nerves to say the least, even though you know that if the balloon takes fire, you have a parachute to drop with.

Again the enemy's battery may be situated so that the balloon man cannot find its location. In this case the airplane solves the problem, for it goes to any desired height, then scouts over the enemy's trenches and does the "spotting." Of course, communication with an airplane is not as easy as with a balloon which has wires running to it, but the airplane can send wireless messages down, which are received on the earth, and to make up for the impossibility of the aviator receiving them in return, owing to the noise of his powerful motor, the men on the ground use a system of signals like the wigwag flag method. This is done by large panels which are in distinct contrast to their background, and move according to a certain code.