1800 to 1837
By 1800 the Jiaqing Emperor was ruling without the influence of the Qianlong Emperor but he was ruling over a China reeling on all fronts. Broke from corruption and endless wars on the periphery against the western tribes, the Viets, and internal rebellions it was also dealing with the growing power of the European trading companies with whom China had always tried to control but had always found mixed success as the Europeans had better technology and were constantly attempting to push the limits imposed by Peking. Leading the European traders were the British who desired above all else to create a favorable trade balance between themselves and the Chinese. However Britain had no goods China desired so it began shipping Indian opium to China in a move that was deeply unpopular with the Chinese court.
Operations in China by the Europeans lulled during the height of the Napoleonic Wars but in the aftermath of those wars the Europeans turned to Asian trade in an attempt to refill their treasuries. This led to the organizing of the Quadruple Alliance of Britain, Russia, France, and the German East India Company with the goal of working together on all fronts to weaken China and create a favorable economic situation (this alliance became the Quintuple Alliance after 1821 with the inclusion of the Portuguese Empire).
China's first real experience with the alliance came in 1834 when the Daoguang Emperor made the fateful decision to support the child emperor Heonjong and his mother/regent the former Empress Sunwon against the claimant emperor Munjo and his European allies in the War of the Korean Succession. Daoguang desired to reaffirm Korea as a Chinese puppet state while expelling the Europeans and securing China for the Chinese. However, while Daoguang had the numerical superiority on the land he was ill prepared for the preparations made by the Quintuple Alliance. Russians inspired uprisings in Chinese Turkestan, invaded Manchuria with a formidable army, and the other Europeans attacked the Chinese coast at will with great success. When a coalition naval force captured Sunwon and the boy emperor, Urumqi fell in Turkestan, the Royal Navy took Tianjin, and the Russians were less than 400 miles from Peking the writing was on the wall and Daoguang sued for peace and signed the humiliating Treaty of Peking in 1837. The downfall of China emboldened the European powers to expand the ongoing Asian Wars and had repercussions in places from Korea to Japan to India. Furthermore the Daoguang Emperor was forced to abdicate in favor of his brother the new Guangxu Emperor.
1838 to Present