During the First Opium War, he was on board the East India Company steamer "Nemesis" during most of the battles. In January 1841, he negotiated terms with Chinese Imperial Commissioner Qishan in the Convention of Chuenpi. Elliot declared via a , among other terms, the cession of Hong Kong Island to the United Kingdom. However, Palmerston recalled Elliot and, accusing him of disobedience and treating his instructions as "waste paper", dismissed him. Henry Pottinger was appointed to replace him as plenipotentiary in May 1841. On 29 July, HMS "Phlegeton" arrived in Hong Kong with dispatches informing Elliot of the news. Pottinger arrived in Macao on 10 August, and announced two days later that Elliot's arrangements with Hong Kong would remain in place. On 24 August, Elliot left Macao with his family for England. As he embarked on the "Atlanta", a Portuguese fort fired a 13-gun salute.