First Opium War

Direct maritime trade between Europe and China began in 1557 when the Portuguese Empire leased an outpost from the Ming dynasty in Macau. Other European nations soon followed the Portuguese lead, inserting themselves into the existing Asian maritime trade network to compete with Arab, Chinese, Indian, and Japanese merchants in intraregional commerce. After the Spanish conquest of the Philippines, the exchange of goods between China and Europe accelerated dramatically. From 1565, the Manila galleons brought silver into the Asian trade network from mines in South America. China was a primary destination for the precious metal, as the imperial government mandated that Chinese goods could only be exported in exchange for silver bullion.

British ships began to appear sporadically around the coasts of China from 1635 on. Without establishing formal relations through the Chinese tributary system, by which most Asian nations were able to negotiate with China, British merchants were only allowed to trade at the ports of Zhoushan, Xiamen (or Amoy), and Guangzhou. Official British trade was conducted through the auspices of the British East India Company, which held a royal charter for trade with the Far East. The East India Company gradually came to dominate Sino-European trade from its position in India and due to the strength of the Royal Navy.

Trade benefited after the newly risen Qing dynasty relaxed maritime trade restrictions in the 1680s. Formosa (Taiwan) came under Qing control in 1683 and rhetoric regarding the tributary status of Europeans was muted. Guangzhou became the port of preference for incoming foreign trade. Ships did try to call at other ports, but these locations could not match the benefits of Guangzhou's geographic position at the mouth of the Pearl River, nor did they have the city's long experience in balancing the demands of Beijing with those of Chinese and foreign merchants. From 1700 onward Guangzhou was the centre of maritime trade with China, and this market process was gradually formulated by Qing authorities into the "Canton System". From the system's inception in 1757, trading in China was extremely lucrative for European and Chinese merchants alike as goods such as tea, porcelain, and silk were valued highly enough in Europe to justify the expenses of travelling to Asia. The system was highly regulated by the Qing government. Foreign traders were only permitted to do business through a body of Chinese merchants known as the Cohong and were forbidden to learn Chinese. Foreigners could only live in one of the Thirteen Factories and were not allowed to enter or trade in any other part of China. Only low-level government officials could be dealt with, and the imperial court could not be lobbied for any reason excepting official diplomatic missions. The Imperial laws that upheld the system were collectively known as the Prevention Barbarian Ordinances (防範外夷規條). The Cohong were particularly powerful in the Old China Trade, as they were tasked with appraising the value of foreign products, purchasing or rebuffing said imports and charged with selling Chinese exports at an appropriate price. The Cohong was made up of between (depending on the politics of Guangzhou) 6 to 20 merchant families. Most of the merchant houses these families ruled had been established by low-ranking mandarins, but several were Cantonese or Han in origin. Another key function of the Cohong was the traditional bond signed between a Cohong member and a foreign merchant. This bond stated that the receiving Cohong member was responsible for the foreign merchant's behavior and cargo while in China. In addition to dealing with the Cohong, European merchants were required to pay customs fees, measurement duties, provide gifts, and hire navigators.

Despite restrictions, silk and porcelain continued to drive trade through their popularity in Europe, and an insatiable demand for Chinese tea existed in Britain. From the mid-17th century onward around 28 million kilograms/61.6 million pounds of silver were received by China, principally from European powers, in exchange for Chinese products.

A brisk trade between China and European powers continued for over a century. While this trading heavily favoured the Chinese and resulted in European nations sustaining large trade deficits, the demand for Chinese goods continued to drive commerce. In addition, the colonisation and conquest of the Americas resulted in European nations (namely Spain, Great Britain, and France) gaining access to a cheap supply of silver, resulting in European economies remaining relatively stable despite the trade deficit with China. This silver was also shipped across the Pacific Ocean to China directly, notably through the Spanish-controlled Philippines. In stark contrast to the European situation, Qing China sustained a trade surplus. Foreign silver flooded into China in exchange for Chinese goods, expanding the Chinese economy but also causing inflation and forming a Chinese reliance on European silver.

The continued economic expansion of European economies in 17th and 18th centuries gradually increased the European demand for precious metals, which were used to mint new coins; this increasing need for hard currency to remain in circulation in Europe reduced the supply of bullion available for trade in China, driving up costs and leading to competition between merchants in Europe and European merchants who traded with the Chinese. This market force resulted in a chronic trade deficit for European governments, who were forced to risk silver shortages in their domestic economies to supply the needs of their merchants in Asia (who as private enterprises still turned a profit by selling valuable Chinese goods to consumers in Europe). This gradual effect was greatly exacerbated by a series of large-scale colonial wars between Great Britain and Spain in the mid 18th century; these conflicts disrupted the international silver market and eventually resulted in the independence of powerful new nations, namely the United States and Mexico. Without cheap silver from the colonies to sustain their trade, European merchants who traded with China began to take silver directly out of circulation in the already-weakened economies of Europe to pay for goods in China. This angered governments, who saw their economies shrink as a result, and fostered a great deal of animosity towards the Chinese for their restriction of European trade. The Chinese economy was unaffected by fluctuations in silver prices, as China was able to import Japanese silver to stabilise its money supply. European goods remained in low demand in China, ensuring the longstanding trade surplus with the European nations continued. Despite these tensions, trade between China and Europe grew by an estimated 4% annually in the years leading up to the start of the opium trade.

Opium as a medicinal ingredient was documented in Chinese texts as early as the Tang dynasty (618–907), but recreational usage of the drug was limited. As with India, opium (then limited by distance to a dried powder, often drunk with tea or water) was introduced to China and Southeast Asia by Arab merchants. The Ming dynasty banned tobacco as a decadent good in 1640, and opium was seen as a similarly minor issue. The first restrictions on opium were issued by the Qing in 1729 when madak (a substance made from powdered opium blended with tobacco) was banned. At the time, madak production used up most of the opium being imported into China, as pure opium was difficult to preserve. Consumption of Javanese opium rose in the 18th century, and after the Napoleonic Wars resulted in the British occupying Java from 1811 to 1816, British merchants became the primary traders in opium. The British realised they could reduce their trade deficit with Chinese manufactories by counter-trading in narcotic opium, and therefore efforts were made to produce more opium in Company-controlled India. Limited British sales of Indian opium began in 1781, with exports to China increasing as the East India Company solidified its control over India.

The British opium was produced in Bengal and in the Ganges river plain, where the British inherited an existing opium-industry from the declining Mughal Empire and identified the product as a potentially valuable export. The East India Company commissioned and managed hundreds of thousands of poppy plantations. It took care of the painstaking lancing of individual pods to obtain the raw gum, drying and forming it into cakes, before coating and packaging them for auction in Calcutta (present-day Kolkata). The Company tightly controlled the opium industry, and all opium was considered Company property until it was sold. From Calcutta, the Company's Board of Customs, Salt, and Opium concerned itself with quality control by managing the way opium was packaged and shipped. No poppies could be cultivated without the Company's permission, and the Company banned private businesses from refining opium. All opium in India was sold to the Company at a fixed rate, and the company hosted a series of public opium-auctions every year. The difference between the Company-set price of raw opium and the sale price of refined opium at auction (minus expenses) was profit made by the East India Company. In addition to securing poppies cultivated on lands under its direct control, the Company's board issued licences to the independent princely states of Malwa, where significant quantities of poppies were grown.

By the late 18th century, Company and Malwan farmlands (which were traditionally dependent on cotton-growing) had been hard hit by the introduction of factory-produced cotton cloth, which used cotton grown in Egypt or in the American South. Opium was considered a lucrative replacement, and was soon being auctioned in ever larger amounts in Calcutta. Private merchants who possessed a Company charter (to comply with the British royal charter for Asiatic trade) bid on and acquired goods at the Calcutta auction before sailing to Southern China. British ships brought their cargoes to islands off the coast, especially Lintin Island, where Chinese traders with fast and well-armed small boats took the goods inland for distribution, paying for the opium with silver. The Qing administration initially tolerated opium importation because it created an indirect tax on Chinese subjects, as increasing the silver supply available to foreign merchants through the sale of opium encouraged Europeans to spend more money on Chinese goods. This policy provided the funds which British merchants needed to then greatly increase tea exports from China to England, delivering further profits to the Qing monopoly on tea exports held by China's imperial treasury and its agents in Guangzhou.

However, opium usage continued to grow in China, adversely affecting social stability. From Guangzhou, the habit spread outwards to the North and West, affecting members from every class of Chinese society. By the early 19th century, more and more Chinese were smoking Indian opium as a recreational drug. For many, what started as recreation soon became a punishing addiction: many people who stopped ingesting opium suffered chills, nausea, and cramps, and sometimes died from withdrawal. Once addicted, people would often do almost anything to continue to get access to the drug. These serious social issues eventually led to the Qing government issuing an edict against the drug in 1780, followed by an outright ban in 1796, and an order from the governor of Guangzhou to stop the trade in 1799. To circumvent the increasingly stringent regulations in Guangzhou, foreign merchants bought older ships and converted them into floating warehouses.

By 1838, the British were selling roughly 1,400 long tons (1,400,000 kg) of opium per year to China. Legalization of the opium trade was the subject of ongoing debate within the Chinese administration, but a proposal to legalise the narcotic was repeatedly rejected, and by 1838 the government had begun to impose increasingly severe penalties on Chinese drug traffickers. Opinions were polarized into two sides. One side adopted a pragmatic approach that favored regulating the opium trade rather than maintaining strict prohibition. Officials such as Xu Naiji argued that the importation and sale should be legalized and then taxed by the Chinese government. Their belief was that legalization and taxation could reduce smuggling, generate additional government revenue, and help address revenue shortages associated with the outflow of silver. The other side, later led by, Lin Zexu, argued that the opium trade was a moral issue and an "evil" that needed to be eliminated.

There were also long-term factors that pushed the Chinese government into action. Historian Jonathan D. Spence lists these factors that led to war:

the social dislocations that began to appear in the Qing world, the spread of addiction, the growth of a hard-line mentality toward foreigners, foreign refusal to accept Chinese legal norms, changes in international trade structures, and the ending of Western intellectuals' admiration for China.... When the tough prohibitions of 1838 began to take effect, the market diminished and dealers found themselves dangerously oversupplied. A second contributing factor was that the new British post of superintendent of foreign trade in China was held by a deputy of the British crown....If the Chinese crossed the superintendent, they would be insulting the British nation rather than the business corporation....[The superintendent could] call directly on the aid of British armed Forces and the Royal Navy in times of serious trouble.

In 1839, the Daoguang Emperor appointed scholar-official Lin Zexu to the post of Special Imperial Commissioner with the task of eradicating the opium trade. Lin's famous open "Letter To Queen Victoria" appealed to Queen Victoria's moral reasoning. Citing what he mistakenly understood to be a strict prohibition on opium within Great Britain, Lin questioned how Britain could declare itself moral while its merchants profited from the legal sale in China of a drug that was banned in Britain. He wrote: "Your Majesty has not before been thus officially notified, and you may plead ignorance of the severity of our laws, but I now give my assurance that we mean to cut this harmful drug forever." The letter never reached the Queen, with one source suggesting that it was lost in transit. Lin pledged that nothing would divert him from his mission, "If the traffic in opium were not stopped a few decades from now we shall not only be without soldiers to resist the enemy, but also in want of silver to provide an army." Lin banned the sale of opium and demanded that all supplies of the drug be surrendered to the Chinese authorities. He also closed the Pearl River Channel, trapping British traders in Guangzhou. As well as seizing opium stockpiles in warehouses and the thirteen factories, Chinese troops boarded British ships in the Pearl River and South China Sea before destroying the opium on board.

The British Superintendent of Trade in China, Charles Elliot, protested the decision to forcibly seize the opium stockpiles. He ordered all ships carrying opium to flee and prepare for battle. Lin responded by besieging the foreign dealers in the foreign quarter of Guangzhou, and kept them from communicating with their ships in port. To defuse the situation, Elliot convinced the British traders to cooperate with Chinese authorities and hand over their opium stockpiles with the promise of eventual compensation for their losses by the British government. While this amounted to a tacit acknowledgment that the British government did not disapprove of the trade, it also placed a huge liability on the exchequer. This promise, and the inability of the British government to pay it without causing a political storm, was used as an important casus belli for the subsequent British attack. During April and May 1839, British and American dealers surrendered 20,283 chests and 200 sacks of opium. The stockpile was publicly destroyed on the beach outside Guangzhou.

After the opium was surrendered, trade was restarted on the strict condition that no more opium be shipped into China. Looking for a way to effectively police foreign trade and purge corruption, Lin and his advisers decided to reform the existing bond system. Under this system, a foreign captain and the Cohong merchant who had purchased the goods off of his ship swore that the vessel carried no illegal goods. Upon examining the records of the port, Lin was infuriated to find that in the 20 years since opium had been declared illegal, not a single infraction had been reported. As a consequence, Lin demanded that all foreign merchants and Qing officials sign a new bond promising not to deal in opium under penalty of death. The British government opposed their signing of the bond, feeling that it violated the principle of free trade, but some merchants who did not trade in opium (such as Olyphant & Co.) were willing to sign against Elliot's orders. Trade in regular goods continued unabated, and the scarcity of opium caused by the seizure of the foreign warehouses caused the black market to flourish. Some newly arrived merchant ships were able to learn of the ban on opium before they entered the Pearl River estuary, and so they unloaded their cargoes at Lintin Island. The opportunity caused by the sharp rise in the price of opium was seized upon by some of the Cohong trading houses and smugglers, who were able to evade commissioner Lin's efforts and smuggled more opium into China. Superintendent Elliot was aware of the smugglers' activities on Lintin and was under orders to stop them, but feared that any action by the Royal Navy could spark a war and withheld his ships.

In early July 1839 a group of British merchant sailors in Kowloon became intoxicated after consuming rice liqueur. Two of the sailors became agitated with and beat to death Lin Weixi, a villager from nearby Tsim Sha Tsui. Superintendent Elliot ordered the arrest of the two men, and paid compensation to Lin's family and village. However, he refused a request to turn the sailors over to Chinese authorities, fearing they would be killed in accordance with the Chinese legal code. Commissioner Lin saw this as an obstruction of justice and Chinese sovereignty, therefore he ordered the sailors to be handed over. Elliot instead held a trial for the accused men aboard a warship at sea, with himself serving as the judge and merchant captains serving as jurors. He invited the Qing authorities to observe and comment on the proceedings, but the offer was declined. The naval court convicted 5 sailors of assault and rioting, and sentenced them to fines along with hard labour in Britain (a verdict later overturned in British courts).

Angered by the violation of China's sovereignty, Lin recalled Chinese labourers from Macau and issued an edict preventing the sale of food to the British. War Junks were deployed to the mouth of the Pearl River, while signs were placed and rumours spread by the Qing that they had poisoned the freshwater springs traditionally used to restock foreign merchant ships. On 23 August a ship belonging to a prominent opium merchant was attacked by lascar pirates while travelling downriver from Guangzhou to Macau. Rumors spread among the British that it had been Chinese soldiers who had attacked the ship, and Elliot ordered all British ships to leave the coast of China by 24 August. That same day Macau barred British ships from its harbour at the request of Lin. The commissioner travelled in person to the city, where he was welcomed by some of the inhabitants as a hero who had restored law and order. The flight from Macau ensured that by the end of August over 60 British ships and over 2000 people were idling off of the Chinese coast, fast running out of provisions. On 30 August HMS Volage arrived to defend the fleet from a potential Chinese attack, and Elliot warned Qing authorities in Kowloon that the embargo on food and water must be ended soon.

Early on 4 September Elliot dispatched an armed schooner and a cutter to Kowloon to buy provisions from Chinese peasants. The two ships approached three Chinese war junks in the harbour and requested permission to land men in order to procure supplies. The British were allowed through and basic necessities were provided to the British by Chinese sailors, but the Chinese commander inside Kowloon fort refused to allow the locals to trade with the British and confined the townspeople inside the settlement. The situation grew more intense as the day went on, and in the afternoon Elliot issued an ultimatum that, if the Chinese refused to allow the British to purchase supplies, they would be fired upon. A 3:00 pm deadline set by Elliot passed and the British ships opened fire on the Chinese vessels. The junks returned fire, and Chinese gunners on land began to fire at the British ships. Nightfall ended the battle, and the Chinese junks withdrew, ending what would be known as the Battle of Kowloon. Many British officers wanted to launch a land attack on Kowloon fort the next day, but Elliot decided against it, stating that such an action would cause "great injury and irritation" to the town's inhabitants. After the skirmish, Elliot circulated a paper in Kowloon, reading;

The men of the English nation desire nothing but peace; but they cannot submit to be poisoned and starved. The Imperial cruisers they have no wish to molest or impede; but they must not prevent the people from selling. To deprive men of food is the act only of the unfriendly and hostile.

Having driven off the Chinese ships, the British fleet began to purchase provisions from the local villagers, often with the aid of bribed Chinese officials in Kowloon. Lai Enjue, the local commander at Kowloon, declared that a victory had been won against the British. He claimed that a two masted British warship had been sunk, and that 40–50 British had been killed. He also reported that the British had been unable to acquire supplies, and his reports severely understated the strength of the Royal Navy.

In late October 1839, the merchant ship Thomas Coutts arrived in China and sailed to Guangzhou. Thomas Coutts's Quaker owners refused on religious grounds to deal in opium, a fact of which the Chinese authorities were aware. The ship's captain, Warner, believed Elliot had exceeded his legal authority by banning the signing of the "no opium trade" bond, and negotiated with the governor of Guangzhou. Warner hoped that all British ships not carrying opium could negotiate to legally unload their goods at Chuenpi, an island near Humen.

To prevent other British ships from following Thomas Coutts's precedent, Elliot ordered a blockade of British shipping in the Pearl River. Fighting began on 3 November 1839, when a second British ship, Royal Saxon, attempted to sail to Guangzhou. The Royal Navy ships HMS Volage and HMS Hyacinth fired warning shots at Royal Saxon. In response to this commotion, a fleet of Chinese war junks under the command of Guan Tianpei sailed out to protect Royal Saxon. The ensuing Battle of Chuenpi resulted in the destruction of 4 Chinese war junks and the withdrawal of both fleets. The Qing navy's official report on the Battle of Chuenpi claimed that the navy had protected the British merchant vessel and reported a great victory for the day. In reality, the Chinese had been out-classed by the British vessels and several Chinese ships were disabled.

The Chinese naval forces in Guangzhou were under the command of Admiral Guan Tianpei, who had fought the British at Chuenpi. The Qing southern army and garrisons were under the command of General Yang Fang. Overall command was invested in the Daoguang Emperor and his court. The Chinese government initially believed that, as in the 1834 Napier Affair, the British had been successfully expelled. Few preparations were made for a British reprisal, and the events leading to the eventual outbreak of the Sino-Sikh War in 1841 were seen as a greater cause for concern.

Left without a major base of operations in China, the British withdrew their merchant shipping from the region while maintaining the Royal Navy's China squadron in the islands around the mouth of the Pearl River. From London, Palmerston continued to dictate operations in China, ordering the East India Company to divert troops from India in preparation for a limited war against the Chinese. It was decided that the war would not be fought as a full-scale conflict, but rather as a punitive expedition. Superintendent Elliot remained in charge of Britain's interests in China, while Commodore Gordon Bremer led the Royal Marines and the China Squadron. Major General Hugh Gough was selected to command the British land forces, and was promoted to overall commander of British forces in China. The cost of the war would be paid by the British Government. Per Lord Palmerston's letter, plans were drawn up by the British to launch a series of attacks on Chinese ports and rivers.

British plans to form an expeditionary force were started immediately after the January 1840 vote. Several infantry regiments were raised in the British isles, and the completion of ships already under construction was expedited. To conduct the upcoming war, Britain also began to draw on forces from its overseas empire. British India had been preparing for a war since word had arrived that the opium had been destroyed, and several regiments of Bengali volunteers had been recruited to supplement the regular British Indian Army and East India Company forces. In terms of naval forces, the ships earmarked for the expedition were either posted in remote colonies or under repair, and Oriental Crisis of 1840 (and the resulting risk of war between Britain, France, and the Ottoman Empire over Syria) drew the attention of the Royal Navy's European fleets away from China. Orders were dispatched to British South Africa and Australia to send ships to Singapore, the assigned rendezvous point for the expedition. A number of steamers were purchased by the Royal Navy and attached to the expedition as transports. The unseasonable summer weather of India and the Strait of Malacca slowed the British deployment, and a number of accidents decreased the combat readiness of the expedition. Most notably, both of the 74-gun ships of the line that the Royal Navy intended to use against Chinese fortifications were temporarily put out of action by hull damage. Despite these delays, by mid-June 1840 British forces had begun to assemble in Singapore. While they waited for more ships to arrive, the Royal Marines practised amphibious invasions on the beach, first by landing ashore in boats, then forming lines and advancing on mock fortifications.

In late June 1840 the first part of the expeditionary force arrived in China aboard 15 barracks ships, four steam-powered gunboats and 25 smaller boats. The flotilla was under the command of Commodore Bremer. The British issued an ultimatum demanding the Qing Government pay compensation for losses suffered from interrupted trade and the destruction of opium, but were rebuffed by the Qing authorities in Guangzhou.

In his letters, Palmerston had instructed the joint plenipotentiaries Elliot and his cousin Admiral George Elliot to acquire the cession of at least one island for trade on the Chinese coast. With the British expeditionary force now in place, a combined naval and ground assault was launched on the Zhoushan (Chusan) Archipelago. Zhoushan Island, the largest and best defended of the islands was the primary target for the attack, as was its vital port of Dinghai. When the British fleet arrived off Zhoushan, Elliot demanded the city surrender. The commander of the Chinese garrison refused the command, stating that he could not surrender and questioning what reason the British had for harassing Dinghai, as they had been driven out of Guangzhou. Fighting began, a fleet of 12 small junks was destroyed by the Royal Navy, and British marines captured the hills to the south of Dinghai.

The British captured the city itself after an intense naval bombardment on 5 July forced the surviving Chinese defenders to withdraw. The British occupied Dinghai harbour and prepared to use it as a staging point for operations in China. In the fall of 1840 disease broke out in the Dinghai garrison, forcing the British to evacuate soldiers to Manila and Kolkata. By the beginning of 1841 only 1900 of the 3300 men who had originally occupied Dinghai were left, with many of those remaining incapable of fighting. An estimated 500 British soldiers died from disease, with the Cameron and Bengali volunteers suffering the most deaths, while the Royal Marines were relatively unscathed.

Having captured Dinghai, the British expedition divided its forces, sending one fleet south to the Pearl River while sending a second fleet north to the Yellow Sea. The northern fleet sailed to the Hai River, where Elliot personally presented Palmerston's letter to the emperor to Qing authorities from the capital. Qishan, a high-ranking Manchu official, was selected by the Imperial Court to replace Lin as the Viceroy of Liangguang after the latter was discharged for his failure to resolve the opium situation. Negotiations began between the two sides, with Qishan serving as the primary negotiator for the Qing and Elliot serving as the representative for the British Crown. After a week of negotiations, Qishan and Elliot agreed to relocate to the Pearl River for further negotiations. In return for the courtesy of the British to withdraw from the Yellow Sea, Qishan promised to requisition imperial funds as restitution for British merchants who had suffered damages. The war, however, was not concluded and both sides continued to engage each other. In the late spring of 1841 reinforcements arrived from India in preparation for an offensive against Guangzhou. A flotilla of transports brought 600 men of the professionally trained 37th Madras Native Infantry to Dinghai, where their arrival boosted British morale. Accompanying the fleet as far as Macau was the newly constructed iron steamer HEICS Nemesis, a weapon to which the Chinese navy had no effective counter. On 19 August three British warships and 380 marines drove the Chinese from the land bridge (known as "The Barrier") separating Macau from mainland China. The defeat of the Qing soldiers coupled with the arrival of the Nemesis in Macau's harbour resulted in a wave of pro-British support in the city, and several Qing officials were driven out or killed. Portugal remained neutral in the conflict, but after the battle was willing to allow British ships to dock in Macau, a decision that granted the British a functioning port in Southern China. With the strategic harbours of Dinghai and Macau secured, the British began to focus on the war on the Pearl River. Five months after the British victory at Chusan, the northern elements of the expedition sailed south to Humen, known to the British as The Bogue. Bremer judged that gaining control of the Pearl River and Guangzhou would put the British in a strong negotiating position with the Qing authorities, as well as allow for the renewal of trade when the war ended.

While the British campaigned in the north, Qing Admiral Guan Tianpei greatly reinforced the Qing positions in Humen (Bocca Tigris), suspecting that the British would attempt to force their way up the Pearl River to Guangzhou; sources state that Guan had been preparing for an eventual attack on the position since Napier's attack in 1835. The Humen forts blocked transit of the river, and were garrisoned with 3000 men and 306 cannons. By the time the British fleet was ready for action, 10,000 Qing soldiers were in position to defend Guangzhou and the surrounding area. The British fleet arrived in early January, and began to bombard the Qing defences at Chuenpi after a group of Chinese fire-rafts were sent drifting towards the Royal navy ships.

On 7 January 1841, the British won a decisive victory in the Second Battle of Chuenpi, destroying 11 Junks of the Chinese southern fleet and capturing the Humen forts. The victory allowed the British to set up a blockade of The Bogue, a blow that forced the Qing navy to retreat upriver.

Knowing the strategic value of Pearl River Delta to China and aware that British naval superiority made a reconquest of the region unlikely, Qishan attempted to prevent the war from widening further by negotiating a peace treaty with Britain. On 21 January Qishan and Elliot drafted the Convention of Chuenpi, a document which both parties hoped would end the war. The convention would establish equal diplomatic rights between Britain and China, exchange Hong Kong Island for Zhoushan, facilitate the release of shipwrecked and kidnapped British citizens held by the Chinese, and reopen trade in Guangzhou by 1 February 1841. China would also pay six million silver dollars as recompense for the opium destroyed at Humen in 1838. However, the legal status of the opium trade was not resolved and instead left open to be discussed at a future date. Despite the success of the negotiations between Qishan and Elliot, both of their respective governments refused to sign the convention. The Daoguang Emperor was infuriated that Qing territory would be given up in a treaty that had been signed without his permission, and ordered Qishan arrested (he was later sentenced to death; the sentence was then commuted to military service.) Lord Palmerston recalled Elliot from his post and refused to sign the convention, wanting more concessions to be forced from the Chinese per his original instructions.

The brief interlude in the fighting ended in the beginning of February after the Chinese refused to reopen Guangzhou to British trade. On 19 February a longboat from Nemesis came under fire from a fort on North Wangtong Island, prompting a British response. The British commanders ordered another blockade of the Pearl River and resumed combat operations against the Chinese. The British captured the remaining Bogue forts on 26 February during the Battle of the Bogue and the Battle of First Bar on the following day, allowing the fleet to move further upriver towards Guangzhou. Admiral Tianpei was killed in action during the fighting on 26 February. On 2 March the British destroyed a Qing fort near Pazhou and captured Whampoa, an action that directly threatened Guangzhou's east flank. Major General Gough, who had recently arrived from Madras aboard HMS Cruizer, personally directed the attack on Whampoa. Superintendent Elliot (who was unaware that he had been dismissed), and the Governor-General of Guangzhou declared a 3-day truce on 3 March. Between the 3rd and the 6th the British forces that had evacuated Zhoushan per the Convention of Chuenpi arrived in the Pearl River. The Chinese military was likewise reinforced, and by 16 March General Yang Fang commanded 30,000 men in the area surrounding Guangzhou.

While the main British fleet prepared to sail up the Pearl River to Guangzhou, a group of three warships departed for the Xi River estuary, intending to navigate the waterway between Macau and Guangzhou. The fleet, led by Captain James Scott and Superintendent Elliot, was composed of the frigate HMS Samarang and the steamships HEIC ship Nemesis and HMS Atalanta.

The war ended in the signing of China's first unequal treaty, the Treaty of Nanking. In the supplementary Treaty of the Bogue, the Qing empire also recognised Britain as an equal to China and gave British subjects extraterritorial privileges in treaty ports. In 1844, the United States and France concluded similar treaties with China, the Treaty of Wanghia and Treaty of Whampoa, respectively.

In addition to opening China to European opium traders, the European trade in captive Chinese coolie labor boomed. Anglophone capitalists referred to this trade collectively as "poison and pigs."

China was required to permit foreign missionaries and the unequal treaties gave European powers jurisdiction over missions and some authority over Chinese Christians.

The opium trade faced intense disapproval from the British politician William Ewart Gladstone, who would later go on to serve as Britain's Prime Minister. Gladstone lambasted the First Opium War as "Palmerston's Opium War" and said in May 1840 that he felt "in dread of the judgments of God upon England for our national iniquity towards China". Gladstone made a famous speech in Parliament against the war, stating, "A war more unjust in its origin, a war more calculated to cover this country with disgrace, I do not know, and I have not read of." His hostility to opium stemmed from the effects opium brought upon his sister Helen. Due to the First Opium war brought on by Palmerston, there was initial reluctance to join the government of Peel on part of Gladstone before 1841.

The war marked the start of what 20th century Chinese nationalists called the "century of humiliation". The ease with which the British forces defeated the numerically superior Chinese armies damaged the dynasty's prestige. The Treaty of Nanking was a step to opening the lucrative Chinese market to global commerce and the opium trade. The interpretation of the war, which was long the standard in the People's Republic of China, was summarised in 1976: The Opium War, "in which the Chinese people fought against British aggression, marked the beginning of modern Chinese history and the start of the Chinese people's bourgeois-democratic revolution against imperialism and feudalism."

The Treaty of Nanking, the Supplementary Treaty of the Bogue, and two French and American agreements were all "unequal treaties" signed between 1842 and 1844. The terms of these treaties undermined China's traditional mechanisms of foreign relations and methods of controlled trade. Five ports were opened for trade, gunboats, and foreign residence: Guangzhou, Xiamen, Fuzhou, Ningbo, and Shanghai. Hong Kong was seized by the British to become a free and open port. Tariffs were abolished thus preventing the Chinese from raising future duties to protect domestic industries and extraterritorial practices exempted Westerners from Chinese law. This made them subject to their own civil and criminal laws of their home country. Most importantly, the opium problem was never addressed and after the treaty was signed opium addiction doubled. China was forced to pay 21 million silver taels as an indemnity, which was used to pay compensation for the traders' opium destroyed by Commissioner Lin. A couple of years after the treaties were signed internal rebellion began to threaten foreign trade. Due to the Qing government's inability to control collection of taxes on imported goods, the British government convinced the Manchu court to allow Westerners to partake in government official affairs. By the 1850s the Chinese Maritime Customs Service, one of the most important bureaucracies in the Manchu Government, was partially staffed and managed by Western Foreigners. In 1858, opium was legalised, and would remain a problem.

Commissioner Lin, often referred to as "Lin the Clear Sky" for his moral probity, was made a scapegoat. He was blamed for ultimately failing to stem the tide of opium imports and usage as well as for provoking an unwinnable war through his rigidity and lack of understanding of the changing world. Nevertheless, as the Chinese nation formed in the 20th century, Lin became viewed as a hero, and has been immortalised at various locations around China.

The First Opium War both reflected and contributed to a further weakening of the Chinese state's power and legitimacy. Anti-Qing sentiment grew in the form of rebellions, such as the Taiping Rebellion, a war lasting from 1850 to 1864 in which at least 20 million Chinese died. The decline of the Qing dynasty was beginning to be felt by much of the Chinese population.

The impact of the opium habit on the Chinese people, and the manner in which the British imposed their power to guarantee the profitable trade, have been staples of Chinese historiography ever since. The British historian Jasper Ridley concluded:

Conflict between China and Britain was inevitable. On the one side was a corrupt, decadent and caste-ridden despotism, with no desire or ability to wage war, which relied on custom much more than force for the enforcement of extreme privilege and discrimination, and which was blinded by a deep-rooted superiority complex into believing that they could assert their supremacy over Europeans without possessing military power. On the other side was the most economically advanced nation in the world, a nation of pushing, bustling traders, of self-help, free trade, and the pugnacious qualities of John Bull.

However, Ridley adds, opposition in Britain was intense:

An entirely opposite British viewpoint was promoted by humanitarians and reformers such as the Chartists and religious nonconformists led by a young Gladstone. They argued that Palmerston (the foreign secretary) was only interested in the huge profits it would bring Britain, and was totally oblivious to the horrible moral evils of opium which the Chinese government was valiantly trying to stamp out.

The American historian John K. Fairbank wrote:

In demanding diplomatic equality and commercial opportunity, Britain represented all the Western states, which would sooner or later have demanded the same things if Britain had not. It was an accident of history that the dynamic British commercial interests in the China trade was centered not only on tea but also on opium. If the main Chinese demand had continued to be for Indian raw cotton, or at any rate if there had been no market for opium in late-Ch'ing China, as there had been none earlier, then there would have been no "opium war". Yet probably some kind of Sino-foreign war would have come, given the irresistible vigor of Western expansion and immovable inertia of Chinese institutions.

Some historians claim that Lord Palmerston, the British Foreign Secretary, initiated the Opium War to maintain the principle of free trade.

Professor Glenn Melancon, for example, argues that the issue in going to war was not opium but Britain's need to uphold its reputation, its honour and its commitment to global free trade. China was pressing Britain just when the British faced serious pressures in the Near East, on the Indian frontier and in Latin America. In the end, says Melancon, the government's need to maintain its honour in Britain and prestige abroad forced the decision to go to war. Former American president John Quincy Adams commented that opium was "a mere incident to the dispute ... the cause of the war is the kowtow—the arrogant and insupportable pretensions of China that she will hold commercial intercourse with the rest of mankind not upon terms of equal reciprocity, but upon the insulting and degrading forms of the relations between lord and vassal."

Ray Huang, in China: A Macro History, provides a broader context for understanding the Opium War. He argues that the causes of the conflict cannot be solely reduced to economic factors or immediate diplomatic tensions. Huang emphasizes the deep structural issues within the Qing dynasty, including economic strain, bureaucratic inefficiencies, and social unrest. These issues weakened the Qing state's ability to respond effectively to both internal and external pressures. The mounting frustrations of Chinese officials and the social dislocations they faced played a significant role in pushing the government towards harsher policies against the opium trade.

The Australian historian Harry G. Gelber argues that opium played a role similar to the tea dumped into the harbour in the Boston Tea Party of 1773 leading to the American Revolutionary War. Gelber argues instead:

The British went to war because of Chinese military threats to defenceless British civilians, including women and children; because China refused to negotiate on terms of diplomatic equality and because China refused to open more ports than Guangzhou to trade, not just with Britain but with everybody. The belief about British "guilt" came later, as part of China's long catalogue of alleged Western "exploitation and aggression".

The Qing government hampered foreign trade and through the Canton System concentrated trade in Guangzhou. That being said, the policy of concentrating trade to a single port was also used in Western countries such as Spain and Portugal. Western merchants could also trade freely and legally with Chinese merchants in Xiamen and Macao or when the trade was conducted through ports outside China such as Manila and Batavia. Furthermore, Macao was restricted to Portuguese traders, and Xiamen the Spanish, who rarely made use of this privilege.

Segments of the public in Britain and American had earlier condemned the British government for supporting the opium trade. Opium was the most profitable single commodity trade of the 19th century. 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." Opium was the most common and the most profitable trade good and comprised 33–54% of all goods shipped from Bengal to the East between 1815 and 1818. Carl Trocki described "the British Empire east of Suez as of 1800 as essentially a drug cartel." James Bradley states that "between 1814 and 1850, the opium trade sucked out 11 percent of China's money supply".

Although shipping was regulated, the Qianlong emperor's administration was diligent in accommodating the requisites of Western merchants. It hired a growing body of Western assistants for the Customs Office to help manage its fellow countrymen. The order to stay in Macao during the winter was lifted; tax was exempted on food, drink, and basic supplies for Western merchants; and protections were granted to Westerners and their property. Qing laws prevented Chinese from pursuing foreigners through the courts. The prohibition mainly dated from the Qianlong Emperor's strong conviction that mistreatment of foreigners had been a major cause of the overthrow of several earlier dynasties.

During the Macartney Embassy, both sides dismissed the gifts given to each other due to underestimating their importance. Instances of British sailors killing Chinese sailors during the late 18th and early 19th centuries, accidentally or otherwise, led to an increasing breakdown in Anglo-Chinese relations. In 1816, the Jiaqing Emperor dismissed a British embassy for its refusal to kowtow, but he sent them an apologetic letter with gifts, which was later found unread in the archives of the Foreign Office in London. Britain's brief occupation of Portuguese Macau during the French Revolutionary and Napoleonic Wars and attacks on American merchantmen in Canton during the War of 1812 along with its support for Nepal during the Sino-Nepalese War and later hostility as part of the Anglo-Nepalese War led the Chinese government 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 the British 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.