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.