18. The United States and the Russian Empire refused to support the British
In April 1857 both the American and Russian governments rejected appeals from Great Britain for an alliance to settle the situation in China. Britain was further delayed in taking decisive action by the Sepoy Rebellion in India, and troops meant for China were forced to be diverted there in the spring of 1857. The French were more open to intervention in China. In February 1856, a French priest, Auguste Chapdelaine, was arrested in Guangxi, where foreigners were forbidden, and in the suspicious and violent atmosphere of the Taiping Rebellion, he was executed for fomenting rebellion. The French wanted revenge.
The French demanded reparations for what they called the murder of the priest, who was killed while violating Chinese law, both entering an area prohibited to foreigners and preaching Christianity outside of the treaty ports. It was clear to the French government that Britain would prevail in a second war with China and dictate the terms of the ensuing peace, and they wanted a seat at the table. The British and French formed a combined force under Admiral Michael Seymour of the Royal Navy, attacking Canton and occupying it in late 1857. The United States was briefly involved earlier in the war when one of its ships was shelled by the Cantonese forts, but the Americans quickly signed a neutrality agreement.