鳥雲山陣
The Bird Cloud Mountain Formation
武王問太公曰：「引兵深入諸侯之地，遇高山盤石，其上亭亭，無有草木，四面受敵，吾三軍恐懼，士卒迷惑，吾欲以守則固，以戰則勝，為之奈何？」太公曰：「凡三軍處山之高，則為敵所棲，處山之下，則為敵所囚。既以被山而處，必為鳥雲之陣。鳥雲之陣，陰陽皆備，或屯其陰，或屯其陽。處山之陽，備山之陰；處山之陰，備山之陽；處山之左，備山之右；處山之右，備山之左。其山敵所能陵者，兵備其表，衢道通谷，絕以武車。高置旌旗，謹敕三軍，無使敵人知我之情，是謂山城。行列已定，士卒已陣，法令已行，奇正已設，各置沖陣於山之表，便兵所處，乃分車騎為鳥雲之陣，三軍疾戰，敵人雖眾，其將可擒。」
King Wu asked Taigong: "If we lead our army deep into hostile territory and encounter a high mountain of solid rock, rising steeply with no vegetation, exposed to attack from all four sides — our three armies are frightened and our soldiers confused — if I wish to make our defense solid and ensure victory in battle, what should be done?" Taigong said: "When the three armies occupy the mountaintop, they become a target for the enemy. When they occupy the base, they become trapped by the enemy. Since you must position forces across the mountain, you must use the Bird Cloud Formation. The Bird Cloud Formation covers both yin and yang aspects: some troops garrison the shaded side, others the sunny side. When occupying the south face, prepare for attack from the north face. When occupying the north face, prepare for the south. When holding the left side, prepare for the right. When holding the right side, prepare for the left. Where the mountain can be scaled by the enemy, station troops to guard the exterior. Block intersecting roads and connecting valleys with war wagons. Raise banners high and strictly instruct the three armies — do not let the enemy know our dispositions. This is called a mountain fortress. Once ranks are set, soldiers deployed, orders enforced, and orthodox and unorthodox elements arranged, place assault formations on the mountain's exterior at convenient positions, then divide chariots and cavalry into the Bird Cloud Formation. When the three armies fight with fury, even if the enemy is numerous, their general can be captured."
Notes
The Bird Cloud Formation (鳥雲之陣) takes its name from the way birds scatter and clouds gather — the formation disperses and reconcentrates fluidly. It is the Liutao's signature tactical innovation for mountain and marsh warfare, appearing in both this chapter and its companion chapter on marsh operations.