[Owing to the double meanings in the Chinese text, the latter part of the sentence is susceptible of quite a different meaning: "And thus, the weapon not being blunted by use, its keenness remains perfect."] This is the method of attacking by stratagem. 8. It is the rule in war, if our forces are ten to the enemy’s one, to surround him; if five to one, to attack him; [Straightway, without waiting for any further advantage.] if twice as numerous, to divide our army into two. [Tu Mu takes exception to the saying; and at first sight, indeed, it appears to violate a fundamental principle of war. Ts’ao Kung, however, gives a clue to Sun Tzŭ’s meaning: "Being two to the enemy’s one, we may use one part of our army in the regular way, and the other for some special diversion." Chang Yu thus further elucidates the point: "If our force is twice as numerous as that of the enemy, it should be split up into two divisions, one to meet the enemy in front, and one to fall upon his rear; if he replies to the frontal attack, he may be crushed from behind; if to the rearward attack, he may be crushed in front." This is what is meant by saying that ‘one part may be used in the regular way, and the other for some special diversion.’ Tu Mu does not understand that dividing one’s army is simply an irregular, just as concentrating it is the regular, strategical method, and he is too hasty in calling this a mistake."] 9. If equally matched, we can offer battle; [Li Ch’uan, followed by Ho Shih, gives the following paraphrase: "If attackers and attacked are equally matched in strength, only the able general will fight."] if slightly inferior in numbers, we can avoid the enemy; [The meaning, "we can _watch_ the enemy," is certainly a great improvement on the above; but unfortunately there appears to be no very good authority for the variant. Chang Yu reminds us that the saying only applies if the other factors are equal; a small difference in numbers is often more than counterbalanced by superior energy and discipline.] if quite unequal in every way, we can flee from him. 10. Hence, though an obstinate fight may be made by a small force, in the end it must be captured by the larger force. 11. Now the general is the bulwark of the State: if the bulwark is complete at all points; the State will be strong; if the bulwark is defective, the State will be weak. [As Li Ch’uan tersely puts it: "Gap indicates deficiency; if the general’s ability is not perfect (i.e. if he is not thoroughly versed in his profession), his army will lack strength."] 12. There are three ways in which a ruler can bring misfortune upon his army:— 13. (1) By commanding the army to advance or to retreat, being ignorant of the fact that it cannot obey. This is called hobbling the army.