29. Military tactics are like unto water; for water in its natural course runs away from high places and hastens downwards. 30. So in war, the way is to avoid what is strong and to strike at what is weak. 31. Water shapes its course according to the nature of the ground over which it flows; the soldier works out his victory in relation to the foe whom he is facing. 32. Therefore, just as water retains no constant shape, so in warfare there are no constant conditions. 33. He who can modify his tactics in relation to his opponent and thereby succeed in winning, may be called a heaven-born captain. 34. The five elements (water, fire, wood, metal, earth) are not always equally predominant; the four seasons make way for each other in turn. There are short days and long; the moon has its periods of waning and waxing. VII. MANŒUVERING 1. Sun Tzŭ said: In war, the general receives his commands from the sovereign. 2. Having collected an army and concentrated his forces, he must blend and harmonise the different elements thereof before pitching his camp. 3. After that, comes tactical manœuvering, than which there is nothing more difficult. The difficulty of tactical manœuvering consists in turning the devious into the direct, and misfortune into gain. 4. Thus, to take a long and circuitous route, after enticing the enemy out of the way, and though starting after him, to contrive to reach the goal before him, shows knowledge of the artifice of _deviation_. 5. Manœuvering with an army is advantageous; with an undisciplined multitude, most dangerous. 6. If you set a fully equipped army in march in order to snatch an advantage, the chances are that you will be too late. On the other hand, to detach a flying column for the purpose involves the sacrifice of its baggage and stores. 7. Thus, if you order your men to roll up their buff-coats, and make forced marches without halting day or night, covering double the usual distance at a stretch, doing a hundred _li_ in order to wrest an advantage, the leaders of all your three divisions will fall into the hands of the enemy. 8. The stronger men will be in front, the jaded ones will fall behind, and on this plan only one-tenth of your army will reach its destination. 9. If you march fifty _li_ in order to outmanœuver the enemy, you will lose the leader of your first division, and only half your force will reach the goal. 10. If you march thirty _li_ with the same object, two-thirds of your army will arrive. 11. We may take it then that an army without its baggage-train is lost; without provisions it is lost; without bases of supply it is lost. 12. We cannot enter into alliances until we are acquainted with the designs of our neighbours. 13. We are not fit to lead an army on the march unless we are familiar with the face of the country—its mountains and forests, its pitfalls and precipices, its marshes and swamps.