Once Cao Cao from Wei led a 200,000 strong army down to the south to wipe out the kingdoms of Wu and Shu. Therefore, Wu and Shu united to defend his attack. Cao ordered his men to link up the boats by iron chains to form a bridge for the Cao's passing from the north bank of Yangtze River to the south bank. The General Commander of the allied army was Zhou Yu. He analyzed the situation carefully. Then he got a good idea. He decided to attack the enemy with fire. So he began to prepare for the coming battle. Suddenly he thought of the direction of wind. He needed the east wind to blow strongly in order to accomplish his scheme. However, the wind did not come for days. Thus Zhou Yu was worried about it. At that time, he got a note from Zhuge Liang, the military adviser of the State of Shu, which reads:

　　    "To fight Cao Cao

　　    Fire will help you win

　　    Everything is ready

　　    Except the east wind"

　　    Quickly he turned to Zhuge Liang for help. Zhuge told him not to worry and there would be an east wind in a couple of days. Two days later, the east wind helped Zhou accomplish his scheme. At last, the allied army won the war.

　　    Later, people use it to say "All is ready except what is crucial".

　　    万事俱备,只欠东风

　　    历史上,中国曾被分为三大国:北边是魏国,西南是蜀国,东南是吴国。

　　    有一次,魏国的曹操带了20万精兵南下攻打吴国和蜀国,准备消灭它们。为了应敌,吴国和蜀国结成同盟国。曹军驻扎在长江北岸。曹操让手下用铁链将战船连在一起,好让曹军渡江攻打南岸的盟军。盟军由吴国将领周瑜带领,他仔细分析了形势,最后决定用火烧掉敌人的船。于是,他开始准备一切,当他将一切准备好时,发现还需要东风。可连续几天都没有东风,周瑜急得病倒了。这时,蜀国的军师诸葛亮叫人送了一张纸条给他,上面写着:"要赢曹操,须用火攻。万事俱备,只欠东风。"周瑜收到后,立刻向诸葛亮求助。诸葛亮叫周瑜不要着急,两天后,将有东风。果然,两天后,刮起东风。周瑜趁这个机会将曹军的战船烧毁,最后,曹操被打败了。

　　    后来,人们用这个成语来比喻样样都准备好了,只差最后一个重要条件。