For 擊, the _T‘ung Tien_ and _Yü Lan_ have 敵. Tu Yu, followed by the other commentators, arbitrarily defines 約 as 少而易勝 “few and easy to conquer,” but only succeeds thereby in making the sentence absolutely pointless. As for Capt. Calthrop’s translation: “In superiority of numbers there is economy of strength,” its meaning is probably known to himself alone. In justification of my own rendering of 約, I would refer to _Lun Yü_ IV. 2 and VII. 25 (3). 16. 吾所與戰之地不可知不可知則敵所備者多敵所備者多則吾所與戰者寡矣 The spot where we intend to fight must not be made known; for then the enemy will have to prepare against a possible attack at several different points; Sheridan once explained the reason of General Grant’s victories by saying that “while his opponents were kept fully employed wondering what he was going to do, _he_ was thinking most of what he was going to do himself.” and his forces being thus distributed in many directions, the numbers we shall have to face at any given point will be proportionately few. 17. 故備前則後寡備後則前寡備左則右寡備右則左寡無所不備則無所不寡 For should the enemy strengthen his van, he will weaken his rear; should he strengthen his rear, he will weaken his van; should he strengthen his left, he will weaken his right; should he strengthen his right, he will weaken his left. If he sends reinforcements everywhere, he will everywhere be weak. In Frederick the Great’s _Instructions to his Generals_ we read: “A defensive war is apt to betray us into too frequent detachment. Those generals who have had but little experience attempt to protect every point, while those who are better acquainted with their profession, having only the capital object in view, guard against a decisive blow, and acquiesce in smaller misfortunes to avoid greater.” 18. 寡者備人者也衆者使人備己者也 Numerical weakness comes from having to prepare against possible attacks; numerical strength, from compelling our adversary to make these preparations against us. The highest generalship, in Col. Henderson’s words, is “to compel the enemy to disperse his army, and then to concentrate superior force against each fraction in turn.” 19. 故知戰之地知戰之日則可千里而會戰 Knowing the place and the time of the coming battle, we may concentrate from the greatest distances in order to fight. There is nothing about “defeating” anybody in this sentence, as Capt. Calthrop translates. What Sun Tzŭ evidently has in mind is that nice calculation of distances and that masterly employment of strategy which enable a general to divide his army for the purpose of a long and rapid march, and afterwards to effect a junction at precisely the right spot and the right hour in order to confront the enemy in overwhelming strength. Among many such successful junctions which military history records, one of the most dramatic and decisive was the appearance of Blücher just at the critical moment on the field of Waterloo. 20. 不知戰地不知戰日則左不能救右右不能救左前不能救後後不能救前而況遠者 數十里近者數里乎