3. When he has penetrated into hostile territory, but to no great distance, it is facile ground.
Li Ch‘üan and Ho Shih say 輕於退也 “because of the facility for retreating,” and the other commentators give similar explanations. Tu Mu remarks: 師出越境必焚舟梁示民無返顧之心 “When your army has crossed the border, you should burn your boats and bridges, in order to make it clear to everybody that you have no hankering after home.” I do not think that “disturbing ground,” Capt. Calthrop’s rendering of 輕地, has anything to justify it. If an idiomatic translation is out of the question, one should at least attempt to be literal.
4. Ground the possession of which imports great advantage to either side, is contentious ground.
I must apologise for using this word in a sense not known to the dictionary, i.e. “to be contended for”—Tu Mu’s 必爭之地. Ts‘ao Kung says: 可以少勝衆弱勝强 “ground on which the few and the weak can defeat the many and the strong,” such as 阨喉 “the neck of a pass,” instanced by Li Ch‘üan. Thus, Thermopylae was a 爭地, because the possession of it, even for a few days only, meant holding the entire invading army in check and thus gaining invaluable time. Cf. Wu Tzŭ, ch. V. ad init.: 以一擊十莫善於阨 “For those who have to fight in the ratio of one to ten, there is nothing better than a narrow pass.” When 呂光 Lü Kuang was returning from his triumphant expedition to Turkestan in 385 A.D., and had got as far as 宜禾 I-ho, laden with spoils, 梁熙 Liang Hsi, administrator of 涼州 Liang-chou, taking advantage of the death of Fu Chien, King of Ch‘in, plotted against him and was for barring his way into the province. 楊翰 Yang Han, governor of 高昌 Kao-ch‘ang, counselled him, saying: “Lü Kuang is fresh from his victories in the west, and his soldiers are vigorous and mettlesome. If we oppose him in the shifting sands of the desert, we shall be no match for him, and we must therefore try a different plan. Let us hasten to occupy the defile at the mouth of the 高梧 Kao-wu pass, thus cutting him off from supplies of water, and when his troops ate prostrated with thirst, we can dictate our own terms without moving. Or if you think that the pass I mention is too far off, we could make a stand against him at the 伊吾 I-wu pass, which is