四月己巳，城濮。前一天，晉侯與宋公、齊國歸父、崔夭、秦小子憖剛在這裡會合；楚軍背對著酅地紮營。開戰之前，晉侯登上有莘的廢墟看自己的隊伍，說了一句：「少長有禮，其可用也！」——《左傳》在這一天之前還記了一筆：晉車七百乘，韅、靷、鞅、靽。就在幾天前，這支軍隊剛往後退了九十里。
退避三舍
退三舍的承諾，是幾年前在楚國許下的。重耳流亡到楚，楚子問他：「公子若反晉國，則何以報不穀？」他答：子女玉帛、羽毛齒革，楚國都有；「若以君之靈，得反晉國，晉楚治兵，遇於中原，其辟君三舍。若不獲命，其左執鞭弭，右屬櫜鞬，以與君周旋。」——若託您的福回到晉國，將來晉楚交戰、在中原相遇，我退您三舍；若還得不到諒解，那就左手執鞭弭、右肩掛弓囊，跟您周旋。當時子玉要殺他，楚子沒答應。
二十八年，這話要兌現了。楚王本來不想打：他命子玉撤圍宋之兵，說「無從晉師」，還引《軍志》三句——「允當則歸」「知難而退」「有德不可敵」——說這三句說的就是晉國。子玉使伯棼請戰，王怒，「少與之師，唯西廣、東宮與若敖之六卒實從之」。子玉使宛春告晉：「請復衛侯而封曹，臣亦釋宋之圍。」先軫出主意：私下許曹、衛復國以離間，執宛春以激怒楚，「既戰而後圖之」。曹、衛果然告絕於楚；子玉怒，從晉師；晉師退。軍吏說：「以君辟臣，辱也。且楚師老矣，何故退？」子犯答：「師直為壯，曲為老，豈在久乎？微楚之惠不及此，退三舍辟之，所以報也。背惠食言，以亢其讎，我曲楚直……若其不還，君退臣犯，曲在彼矣。」——退三舍，楚眾欲止，子玉不可。三十里為一舍，三舍九十里，這是通行說法，兩頁都沒有注。
城濮的陣
到了城濮，氣氛更緊。楚師背酅而舍，晉侯患之；輿人誦「原田每每，舍其舊而新是謀」，他聽了反而起疑；子犯說「戰也」，欒貞子說「漢陽諸姬，楚實盡之。思小惠而忘大恥，不如戰也」。晉侯夢見與楚子搏鬥，楚子伏在他身上吮他的腦，他害怕；子犯解夢說「吉！我得天，楚伏其罪，吾且柔之矣」。接著是兩段辭令：子玉使鬥勃請戰，說「請與君之士戲，君馮軾而觀之，得臣與寓目焉」；晉侯使欒枝對答：「寡君聞命矣。楚君之惠，未之敢忘，是以在此。為大夫退，其敢當君乎？既不獲命矣，敢煩大夫謂二三子：『戒爾車乘，敬爾君事，詰朝將見。』」——明天早上見。
陣形分得清楚。晉：中軍由先軫（原軫）將，郤溱佐；上軍狐毛、狐偃；下軍欒枝、胥臣。楚：子玉以若敖之六卒將中軍，說「今日必無晉矣」；子西將左，子上將右。晉車七百乘，楚軍這邊，《左傳》只記了王所給的那一點——西廣、東宮與若敖之六卒，沒有給總數。
己巳那一天
開合只有幾步。晉師陳於莘北，胥臣以下軍之佐當陳、蔡；「胥臣蒙馬以虎皮，先犯陳、蔡。陳、蔡奔，楚右師潰。」接著是兩記假動作：「狐毛設二旆而退之」；「欒枝使輿曳柴而偽遁」——車後拖柴揚起塵土，裝出逃跑的樣子；「楚師馳之」，追了過來。然後「原軫、郤溱以中軍公族橫擊之」；「狐毛、狐偃以上軍夾攻子西，楚左師潰。楚師敗績」。只有子玉「收其卒而止，故不敗」。
戰後也有帳：晉師「三日館穀」，到癸酉才還；甲午到衡雍，在踐土作王宮；五月獻楚俘，「駟介百乘，徒兵千」；王策命晉侯為侯伯，賜「大輅之服，戎輅之服，彤弓一，彤矢百，玈弓矢千，秬鬯一卣，虎賁三百人」，命辭是「敬服王命，以綏四國，糾逖王慝」。子玉的結局，兩頁說法不同：《春秋》經文只寫「楚殺其大夫得臣」；《史記·晉世家》說楚成王「怒其不用其言，貪與晉戰，讓責子玉，子玉自殺」。
兩頁之間
數字與說法要分層並錄，不能合成一套。兵力：《左傳》給晉「七百乘」，楚只給「西廣、東宮與若敖之六卒」；《史記·晉世家》不載晉車數，只說「己巳，與楚兵合戰，楚兵敗」——兩頁不合，不裁斷，也不把乘數換算成人數。別的異文也一樣：《左傳》數曹伯之罪，是「不用僖負羈而乘軒者三百人」；《史記》作「不用釐負羈言，而用美女乘軒者三百人」。《史記》還多一句「晉焚楚軍，火數日不息」，以及文公戰後行賞的一段——以狐偃「說我毋失信」為萬世之功，先軫「軍事勝為右」為一時之說。這些都不見於《左傳》這一段。
「退避三舍」也可以讀到兩層。《左傳》裡它先是子犯算的直曲帳：退，是為了報楚惠；楚若不還，「君退臣犯，曲在彼矣」。《史記》裡它變成文公口中的「昔在楚，約退三舍，可倍乎」，又變成戰後行賞的理由。兩頁各給一層，本篇並列，不裁斷哪一層才是本意，更不把它引申成「誠信」「仁義」的教材；三十里一舍、九十里，只是照原文與通行說法寫下來。
一天的戰事
這篇只寫這一天：地點城濮，時間四月己巳，晉車七百乘，楚的中軍、左軍、右軍，退三舍的理由，開戰的四步與結果。兩頁都沒有給地圖、沒有給戰場面積、沒有給雙方總兵力；本篇也不補地圖、不補考古。《左傳》自己在僖公二十七年末尾有一句評語「一戰而霸，文之教也」——那是《左傳》的話，可以引，但不當作「晉楚爭霸轉折點」的史論來發揮。
參考來源與延伸閱讀
- 《春秋左氏传》僖公（维基文库本，未与点校本复核） — The full account. The promise in the twenty-third year: 'if by your spirit I return to Jin, and Jin and Chu marshal their armies and meet on the central plain, I will retire three she before you; if I still do not receive your command, then with whip and bow in my left hand and quiver at my right I will have a turn with you' (其辟君三舍……以与君周旋). In the twenty-eighth year: the king of Chu orders Zi Yu not to follow the Jin army and quotes the Military Records; 'he gave him few troops: only the Western Broad, the Eastern Palace and the six companies of Ruo Ao went with him' (唯西广、东宫与若敖之六卒实从之); Wan Chun's proposal and Xian Zhen's counter; the retreat, the officers' objection, and Zi Fan's 'an army is strong when it is straight and old when it is crooked … a lord has retired and a subject has pressed on him, and the crookedness is theirs' (师直为壮，曲为老……君退臣犯，曲在彼矣). At Chengpu: the divination songs, the dream, the two speeches (请与君之士戏……诘朝将见), 'seven hundred chariots of Jin' (晋车七百乘), the lines under Xian Zhen, Hu Mao and Hu Yan, Luan Zhi and Xu Chen, and Zi Yu's centre with Zi Xi left and Zi Shang right; the fighting — tiger skins, two pennants, brushwood dust, 'Yuan Zhen and Xi Zhen with the ducal clan struck across' (原轸、郤溱以中军公族横击之), both Chu wings broken, Zi Yu gathering his men; then three days of Chu's grain, the presentation of prisoners, and the king's charge and gifts. The Chun Qiu text in the same page has 'Chu killed its grand officer Dechen'.
- 《史记》卷三十九·晋世家（西汉司马迁；维基文库本，未与点校本复核） — The parallel account with the differences that matter. The same campaign, with 'three hundred beauties riding in carriages' (用美女乘轩者三百人也) where the Zuo Zhuan has only the three hundred riders; the king of Chu's refusal to fight and his 'few troops'; Wan Chun's mission and Xian Zhen's counter; the retreat justified in the lord of Jin's own words, 'in Chu I promised to retire three she; can I double it?' (昔在楚，约退三舍，可倍乎). The battle is given in one line, with no chariot count: 'on ji-si he joined battle with the Chu army, and the Chu army was defeated' (己巳，与楚兵合战，楚兵败). Then the presentation of prisoners, the king's appointment of the lord of Jin as leader of the lords with the gifts, and the line 'Jin burned the Chu army, and the fire did not go out for several days' (晋焚楚军，火数日不息). Zi Yu's end: the king 'reproached Zi Yu, and Zi Yu killed himself' (让责子玉，子玉自杀). After the battle the lord of Jin ranks the rewards, putting Hu Yan first because 'he told me not to break faith', over Xian Zhen's 'in war victory is the rule' — a judgement the Zuo Zhuan passage does not contain.
