As Timothy Brook and Bob Wakabayashi write of opium, “The British Empire could not survive were it deprived of its most important source of capital, the substance that could turn any other commodity into silver.”
Chinese merchants were actually banned by Qing law from suing foreigners in Chinese courts, as the Qianlong Emperor believed that good treatment of foreigners was essential for the government. The Qianlong Emperor granted Lord Macartney a golden scepter, an important symbol of peace and wealth, but this was dismissed by the British as worthless. In 1806, Chinese officials compromised with the British on the murder of a Chinese man by British seamen, as Westerners refused to be punished under Chinese law, and local citizens vigorously protested what they considered a miscarriage of justice. In 1816, the Jiaqing Emperor dismissed a British embassy for their refusal to kowtow, but he sent them an apologetic letter with gifts (the British simply discarded them in a storeroom without reading). The British, on the other hand, ignored Chinese laws and warnings not to deploy military forces in Chinese waters. The British landed troops in Macao despite a Chinese and Portuguese agreement to bar foreign forces from Macao, and then in the War of 1812 attacked American ships deep in the inner harbour of Canton (the Americans had previously robbed British ships in Chinese waters as well). These, in combination with the British support to Nepal during their invasion of Tibet and later the British invasion of Nepal after it became Chinese tributary state, led the Chinese authorities to become highly suspicious of British intentions. In 1834, when British naval vessels intruded into Chinese waters again, the Daoguang Emperor commented: "How laughable and deplorable is it that we cannot even repel two barbarian ships. Our military had decayed so much. No wonder the barbarians are looking down on us."
Historians have often pondered whether the war could have been avoided. One factor was that China rejected diplomatic relations with Britain, or anyone else, as seen in the rejection of the Macartney mission in 1793 As a result, diplomatic mechanisms for negotiation and resolution were missing. Michael Greenberg locates the inevitable cause in the momentum for more and more overseas trade in Britain's expanding modern economy. On the other hand, the economic forces inside Britain that were war hawks—Radicals in Parliament, and northern merchants and manufacturers—were a political minority and needed allies, especially Palmerston, before they could get their war. In Parliament the Melbourne government faced a host of complex international threats including the Chartist riots at home, bothersome budget deficits, unrest in Ireland, rebellions in Canada and Jamaica, war in Afghanistan, and French threats to British business interests in Mexico and Argentina. The opposition demanded more aggressive answers, and it was Foreign Minister Palmerston who set up an easy war to solve the political crisis. It was not economics, or opium sales or expanding trade that caused the British to go to war, Melancon argues, it was more a matter of upholding aristocratic standards of national honour sullied by Chinese insults.
One historiographical problem is that the emphasis on the British causal factors tends to ignore the Chinese. The Manchu rulers were focused on internal unrest by Chinese elements, and paid little attention to the minor issues happening in Canton. Historian James Polachek argues the reasons for trying to suppress the opium trade had to do with internal factionalism led by a purification-oriented group of literary scholars who paid no attention to the risk of international intervention by much more powerful military forces. Therefore, it was not a matter of inevitable conflict between contrasting worldviews. Lin and the Daoguang Emperor, comments historian Jonathan Spence, "seemed to have believed that the citizens of Canton and the foreign traders there had simple, childlike natures that would respond to firm guidance and statements 