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.