n.
With the Pearl River cleared of Chinese defenses, the British debated advancing on Canton. Although the truce had ended on 6 March, Superintendent Elliot believed that the British should negotiate with the Qing authorities from their current position of strength rather than risk a battle in Canton. The Qing army made no aggressive moves against the British and instead began to fortify the city. Chinese military engineers began to establish a number of mud earthworks on the riverbank, sank junks to create riverblocks, and started constructing fire rafts and gunboats. Chinese merchants were ordered to remove all of the silk and tea from Canton to impede trade, and the local populace was barred from selling food to the British ships on the river. On 16 March a British ship approaching a Chinese fort under a flag of truce was fired upon, leading to the British setting the fort on fire with rockets. These actions convinced Elliot that the Chinese were preparing to fight, and following the return of the ships of the Broadway expedition to the fleet, the British attacked Canton on 18 March, taking the Thirteen Factories with very few casualties and raising the Union Jack above the British factory. The city was partially occupied by the British and trade was reopened after negotiation with the Cohong merchants. After several days of further military successes, British forces commanded the high ground around Canton. Another truce was declared on 20 March. Against the advice of some of his captains, Elliot withdrew most of the Royal Navy warships downriver to the Bocca Tigris.
In mid April Yishan (Qishan's replacement as Viceroy of Liangguang and the Daoguang Emperor's cousin) arrived in Canton. He declared that trade should continue to remain open, sent emissaries to Elliot, and began to gather military assets outside Canton. The Qing army camped outside of the city soon numbered 50,000, and the money earned from the reopened trade was spent repairing and expanding Canton's defenses. Concealed artillery batteries were built along the Pearl River, Chinese soldiers were deployed in Whampoa and the Bocca Tigris, and hundreds of small river craft were armed for war. A bulletin sent from the Daoguang Emperor commanded the Qing forces to "Exterminate the rebels at all points," and orders were given to drive the British from the Pearl River before reclaiming Hong Kong and driving the invaders out of China altogether. This order was leaked and became widely circulated in Canton among foreign merchants, who were already suspicious of Chinese intentions after learning of the Qing military buildup. In May many Cohong merchants and their families left the city, raising further concerns about a renewal of hostilities. Rumors spread that Chinese divers were being trained to drill holes in the hulls of British ships, and that fleets of fire rafts were being prepared for deployment against the Royal Navy. During the buildup the Qing army was weakened by infighting between units and lack of confidence in Yishan, who openly distrusted Cantonese civilians and soldiers, instead choosing to rely on forces drawn from other Chinese provinces. On 20 May Yishan issued a statement, asking the "people of Canton, and all foreign merchants who are respectfully obedient, not to tremble with alarm and be frightened out of their wits at the military hosts that are gathering around, there being no probability of hostilities." The next day Elliot requested that all British merchants evacuate the city by sundown, and several warships were recalled to their positions in front of Canton.
On the night of 21 May the Qing launched a coordinated night attack on the British army and navy. Artillery batteries hidden in Canton and on the Pearl River (many of which the British believed they had disabled earlier) opened fire, and Qing soldiers retook the British Factory. A large formation of 200 fire rafts connected by a chain was sent drifting towards the British ships at Canton, and fishing boats armed with matchlock guns began to engage the Royal Navy. The British wars