有一次，晉武帝派二十萬大軍兵分六路攻打東吳，其中鎮南大將軍杜預，到長江中游樂鄉城時，便派屬下周旨帶著兩百名士兵，趁著天黑渡過長江，渡江後所有士兵都換上吳軍服裝，並埋伏在樂鄉城外。第二天，樂鄉城的守將孫歆帶兵出城，在長江上游和晉軍大戰，吳軍戰敗，軍隊全往樂鄉城方向逃。這時，前一天埋伏的晉軍，就趁機混進吳軍裡一起進城，進城後依照計畫在城裡四處放火。當城裡一片混亂時，周旨帶著軍隊衝入吳軍的指揮中心，將孫歆活捉起來，樂鄉城就被晉軍占領。之後吳軍在各地和晉軍交戰全都戰敗，前後不到五個月，吳國便投降。
三十六計之第二十計：混水摸魚
原指把水弄混濁，讓水中的魚看不清楚，便可趁機抓魚。這裡是指製造混亂的局面，讓敵軍搞不清楚真假及方向，我軍就可以趁機獲利。
Jin Wu Di once sent an army of two hundred thousand soldiers to attack Wu. The Jin army was led by the great general Du Yu. When the Jin army arrived at the city of Yue Siang which was right next to the Yangtze River, his captain Jhou Jhih crossed the river at night with two hundred raiders. Then they all changed into Wu army's uniform, hid themselves outside the city of Yue Siang, and waited in ambush.
The next day, Sun Sin, the general in charge of defending Yue Siang, took his army outside the city walls to fight the Jin army. The Wu army lost the battle, and as the troops fled back to the city of Yue Siang, the two hundred Jin raiders mingled in with the Wu army and entered the city walls during the chaos. Afterwards, they set fires all over the city as planned. And when everything was in chaos, Jhou Jhih and his raiders rushed into the headquarter of the Wu army and caught Sun Sin alive. This was how the city of Yue Siang fell to the Jin army.
The rest of the Wu army was defeated in subsequent battles. In less than five months Wu surrendered to Jin.
Strategy 20 : Catch a Fish While the Water is Disturbed
Originally it means to roil the water sediments in order to cloud the vision of the fish and catch the fish.
Here it means to create confusion so that the enemy does not know what is real and what is not, nor where we are feinting and where we are attacking. This way, a confused enemy is more vulnerable to our attack.
