shan 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 Canton. 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 HMS 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 the Chinese mainland. The defeat of the Qing soldiers coupled with the arrival of the Nemesis in Macau's harbor 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 harbors 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 Canton 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 (sources state that Guan had been preparing for an eventual attack on the position since Napier's attack in 1835) that the British would attempt to force their way up the Pearl River to Canton. The Humen forts blocked transit of the river, and were garrisoned with 3000 men and 306 cannon. By the time the British fleet was ready for action, 10000 Qing soldiers were in position to defend Canton and the surrounding area. The British fleet arrived in early January, and began to bombard the Qing defenses 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 Chusan, facilitate the release of shipwrecked and kidnapped British citizens held by the Chinese, and reopen trade in Canton 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