When an army has penetrated into the heart of a hostile country,
leaving a number of fortified cities in its rear,
After 多, the _T‘ung Tien_ intercalates the gloss 難以返.
it is serious ground.
Wang Hsi explains the name by saying that 兵至此者事勢重也 “when an
army has reached such a point, its situation is serious.” Li
Ch‘üan instances (1) the victorious march of 樂毅 Yo I into the
capital of Ch‘i in 284 B.C., and (2) the attack on Ch‘u, six years
later, by the Ch‘in general 白起 Po Ch‘i.