I imagine it was considered a strategic Tang victory even though it resulted in a loss of the city, because without the time bought by the seige, the Tang would not have been able to put down the rebellion.

Also I learned a lot today and it’s all terrible.

The Taiping Rebellion. Basically a Chinese guy claims to be the brother of Jesus and leads a pro-Christian rebellion against the Qing government that results in more deaths than the first world war