(Before) September 26 1792 - George Macartney set sail from Britain to China carrying gifts to encourage to Chinese emperor to open up trade with the western and modernised world, though Macartney only cared about trade for Britain.
(Before) 1792 - An Employee of the Honourable East India Company thought that the canton system was an undue restriction of free trade and was abuse of Corrupt officials. (Extra Credits 2016) He went to discuss this matter with the Emperor immediately and went the the imperial palace in Beijing because he thought he could talk directly to emperor and the Chinese were very surprised.
(During) During the Opium War 1839–1842, countries such as Russia, Britain, Japan, France and Germany were all fighting for piece of China to increase trade with the country. The example of this in Britains case was when George Macartney went bearing gifts and asked the emperor if they were able to set up a sort of trading headquarters in the island we know today as Hong Kong where they would operate under British Law. This picture below depicts this idea perfectly.
(After) 4 September 1839 - The Battle of Kowloon occurred between British ships and Chinese Junks in 1839 because two drunk British men beat up a Chinese man and the British wanted to prosecute him on British land rather than Chinese. Lin Zexu objected, therefore starting a battle of the two ships.
(After) 1842 - The conclusion of the first Opium War. The war ended between Britain and China due an agreement called The Treaty of Nanjing. This peace treaty contained 16 rules and regulations that benefited both nations so the war was extinguished.