Because at that time Hong Xiuquan had been defeated by the Hunan Army led by Zeng Guofan and was a prisoner of war. At the same time, Zeng Guofan, as an official of the Qing Dynasty, was on the opposite side of Hong Xiuquan, and Hong Xiuquan had defeated Zeng Guofan, which made Zeng Guofan feel very humiliated.
1. Past grievances
Hong Xiuquan and Zeng Guofan had grievances. In the early days of the Taiping Heavenly Kingdom, Hong Xiuquan used his own call to rally a team. In order to consolidate his newly established political power, Hong Xiuquan began the Northern Expedition and the Western Expedition. During the Western Expedition, they were always victorious. At that time, it was Zeng Guofan who faced Hong Xiuquan's troops. Although Zeng Guofan achieved some victories by relying on his ability to command troops, he failed to withstand the attack of the Western Expeditionary Army.
In the end Zeng Guofan even wanted to commit suicide by throwing himself into a lake, but was stopped by his subordinates. From then on, Zeng Guofan hated Hong Xiuquan very much. He also worked hard to make himself stronger, hoping that one day he would be able to avenge his past humiliation. Therefore, after Hong Xiuquan fell into his hands, there would definitely be no good results. And because Hong Xiuquan was very complacent after establishing the political power, the Taiping Heavenly Kingdom also had intrigues with each other, and its overall strength dropped a lot, so it was finally defeated by Zeng Guofan.
2. Two people stood on opposite sides, and Hong Xiuquan was defeated by Zeng Guofan
As the leader of the peasant uprising, Hong Xiuquan must have been on opposite sides of the Qing Dynasty official Zeng Guofan, because the purpose of the Taiping Heavenly Kingdom was to overthrow Qing Dynasty. Moreover, after Zeng Guofan was defeated, he also learned from the painful experience and trained a Hunan army, and finally in the crusade against the Taiping Heavenly Kingdom. With his extraordinary courage and brilliant strategy, he defeated the Taiping Army and put down the Taiping Heavenly Kingdom Movement.
To sum up, the reason why Hong Xiuquan was loaded into a cannon and shot into the sky by Zeng Guofan was because he and Zeng Guofan had a personal grudge. At the same time, due to his personal reasons, the overall strength of the Taiping Heavenly Kingdom declined, so it was unable to withstand Zeng Guofan's attack.