Chinese history can be read as a series of peasant rebellions. One in the 19th Century, led by a man who thought he was Christ's brother, lasted 15 years and caused at least 10 million deaths.
Originally, all Hong Xiuquan wanted was to be part of the establishment. A village schoolteacher, he immersed himself in Confucian scholarship for the civil service exam, but just kept failing.
Some time later he was given a Chinese translation of the New Testament by a Christian missionary. He decided on reading that, that the man he had seen up in the sky was the Christian God, and that he, Hong, was the brother of Jesus, and that the devils he had to exterminate on Earth were the Qing dynasty, which was then ruling China.
The Europeans saw Hong's claim to be the brother of Christ as heresy, but he was not preaching for their benefit. He accompanied his spiritual message with a political one - a vision of equality and shared land, which appealed to poor farmers who were suffering from a sense of hopelessness.
Hong and his disciples took to the road, selling writing brushes and ink and spreading the good news about the heavenly kingdom as they went and their movement grew fast in south-west China.
By 1860, Hong's heavenly kingdom extended across huge swathes of China and his troops were preparing to march on Shanghai. But his luck was about to run out.
The Europeans had decided he was a threat to business and so joined forces with the Qing armies they themselves had just been fighting. In the Heavenly Capital, the Heavenly Kingdom was anything but.
As military victory turned into defeat, Hong became increasingly paranoid, his followers starved and his court spiralled into intrigue and violence.
Presenter: Carrie Gracie
Producer: Neal Razzell.