In Volume I., page 189, I gave you some account of the machine gun which, as you will remember, discharges automatically and accurately some four hundred or five hundred shots a minute. As a rifleman can only fire about a dozen aimed shots in the same time, a machine gun is equivalent to at least thirty riflemen. It discharges its bullets in a cone-shaped stream, and is even more deadly than sustained rifle fire. Prior to the war each battalion in the British army was provided with two machine guns. The German General Staff, however, provided each unit of its infantry with a large number of machine guns,[6] which were so mounted that they could be carried rapidly over every kind of ground. The result was that the Germans had a very marked advantage over the Allies in machine firing power. Here, again, the German theory was correct, and the Allies were forced to follow suit and increase greatly their supply of machine guns. The Germans have no faith in the waiting game. They believe that constant attack is the best form of defence. It is foreign to their ideas to wait for the enemy to attack them; everywhere and always they endeavour to strike at the foe. They believe with the American humorist: "Thrice blessed he who hath his quarrel just, But four times he who gets his blow in fust." In order to enable troops to strike swiftly, and, therefore, to take the enemy unawares, the Germans provided themselves with fleets of motor cars in which they conveyed their soldiers to the points where they were needed. The admirable Belgian and French roads enabled the motors to travel very quickly, and this accounts in large measure for the rapid pursuit of the Allies. The motor cars were meant to be specially useful in making those flanking movements by which German generals strive to envelop their enemies. These flanking attacks, however, were not successful, perhaps because it was impossible to transport sufficient artillery along with the men. [Illustration: The Effect of High Explosive Shells on Trenches. A breach is made in the wire entanglements and the chief force of the explosion is downwards. (_By permission of The Sphere._)] Finally, let me deal for a few moments with a theory that proved to be hopelessly wrong, so entirely mistaken that it robbed the Germans of that speedy victory which they confidently expected, and led to a long and uncertain trench war in the West. What was this theory?