投鞭断流（投鞭斷流）　

◎ 投鞭断流 tóubiān-duànliú

[(of forces) numerous and powerful;with a strong army that,if the soldiers throw their whips into the river,it would be enough to stem the current] 中国前秦的苻坚进攻东晋时骄傲地说,我这么多的军队,把每个兵的马鞭子都投到江里,就能截断水流(见于《晋书·苻坚载记》)。后用来比喻人马众多,兵力强大