There are two ways of breaking an enemy's line. The first way is by holding the enemy all along his line, and suddenly bringing against one part of it a large, powerful force. If this force breaks through, it divides the opposing army, and can beat it in detail. Such an attack is known as a _frontal attack_. Napoleon tried it at Waterloo, but could not break through the "thin red line" of Wellington's heroes. The other way of breaking the enemy's line is to _outflank_ it, and then _envelop_ or surround his forces. I have already used the word _flank_ several times in these pages. It simply means the side or wing. If a man attacks you when you are sideways, you cannot well resist him. In order to do so you must turn your face towards him. So it is with an army. If it is attacked on its side or wing, it cannot properly resist until it forms a line facing the attacker. While it is doing this it runs the risk of being thrown into confusion, and perhaps destroyed. Look at the diagram on p. 216. Let A-F be a British force, and _a-f_ a German force equal in strength. While these forces are fighting front to front, suppose a new British force, G H I, should appear, and attack the flank _a_. It is clear that the soldiers at _a_ can only defend themselves if they swing round to meet the attack of G H I. If they remain where they are, they will very soon have the foe behind them as well as in front of them, and they will then be between two fires, in which case they can hardly escape destruction. [Illustration] Suppose they swing round the two bodies _a_, _b_, as in Figure 1 (p. 217) to meet G H I, what happens? The German line is weakened. Instead of having six bodies to meet six bodies, they have now only four to oppose the six of the attacking force. Immediately E F will try to take _f_ in flank, and soon the line will assume the position shown in Figure 2 (p. 217). You can easily see that the line of the enemy's communications is now in danger, and that if the movement continues the whole force will be surrounded. You will remember that the Germans managed to surround a large French army at Sedan and force it to surrender.[183] When a general finds himself being outflanked by a superior force, he is bound to retreat and straighten out his line again, if he is to save himself from disaster. [Illustration: Fig. 1.] [Illustration: Fig. 2.] In reading war news you will often meet with the word _strategy_, which means the art of generalship, of moving and arranging great bodies of troops in order to put the enemy at a disadvantage, and so overcome him. I have given you some examples of strategy above.