白居易於四十四歲時，因越職論事，上疏要求緝捕暗殺宰相武元衡的盜賊，而被貶為江州司馬。貶江州為白居易仕途的第一次貶謫，對白居易人生觀及創作影響深遠。本文深入探討白居易貶江州一事。首先論及白居易貶江州時順利的仕途，說明白居易在武元衡暗殺事件後立刻上書的舉動，乃白居易認為上書的舉動能引起唐憲宗的重視，希望再度受到皇帝重用，沒料到誤判局勢，反而遭受貶謫的下場。其次論及白居易之所以被貶，乃是當時主戰、反戰兩派衝突的結果，白居易只是眾多被貶的反戰朝臣其中一員，而主導此次大規模貶謫反戰派朝臣的人，乃是宰相裴度。執政貶謫白居易為江州司馬，依唐人貶官慣例，並非重貶。最後論及白居易自己清楚知道貶江州並非重貶，因此在心境上沒有怨懟憤慨，相較於他人，白居易貶謫後，心境相對平靜安和。抵達江州後，白居易在江州重新審視自己的前半生，除了編次自己的詩集外，也重新思考自身詩人身分的價值，確立自己身為詩人的詩人意識。

On the third day of the sixth month of 815, just before dawn, the Chief Minister, Wu Yuan-heng (武元衡), was assassinated when on his way to Court. Bai wrote a Memorial to the Throne demanding that every possible measure should be taken to find and arrest the assassin. But Bai's act was arguable that he had acted mistakenly or even rashly, but he had certainly not been guilty of a punishable crime. The heads of Government were annoyed about Bai's Memorial and Bai was made the sub-prefect of Jiang Zhou state (江州司馬) eventually. In this essay, I want to demonstrate the demotion of Bai that was decided by the Chief Minister, Pei Duo (裴度). As a matter of fact, sub-prefect was not severe punishment to Bai. Pei expelled all the reconciliatory party from the Capital, and Bai was one of them. Bai comprehended it, so he was not too depressed by the effect. When Bai arrived in Jiang Zhou, he reviewed his whole life to be confident of the identity as a poet.