Once upon a time, the State of Chu planned to attack the State of Song. But the Yong River was the natural barrier against its surprise attack at night.

To overcome this obstacle, the State of Chu sent men to secretly measure the depth of the Yong River and make marks for wading across the river at night.

But when night came, the water in the Yong River suddenly rose; yet the Chu army still tried to stealthily cross the river 1000 soldiers were drowned. There was utter chaos of desperate cries and shootings' on the river. All at once, the army collapsed like a fallen building, and was routed.

According to the marks, the Chu army would have been able to cross the Yong River during the day; but the rising water changed the situation in the night. Yet the Chu army still tried to wade across the river according to the marks made in the daytime, so naturally they failed.

古时候，有一次，楚国准备进攻宋国，而澭河水楚国夜间偷袭宋国的天然障碍。

为了越过这个障碍，楚国派人悄悄地去测量澭水的深度，并且做好了夜间涉水过河的标记。

谁知到了夜里，澭河的水暴涨，水位升高。但是，楚国人却仍然按照白天做的标记偷渡，结果淹死了一千多人。河面上哭声喊声一片混乱，顿时，队伍就像房屋倒塌一样，溃不成军。

按照所做的标记，楚军白天使可以度过澭河的；然而，夜间水情已经发生变化，楚军却仍然按照白天的标记渡河，自然他们要失败了。