Early voyages and the Opium War (1840–1842) Under the command of Captain Richard Francis Cleaveland,
Phlegethon departed England on 11 August 1840. Despite encountering severe storms in the Mozambique Passage, her improved longitudinal construction prevented the structural damage that had plagued earlier iron vessels. By July 1841, the
Phlegethon had joined the British fleet in Hong Kong for operations in the
First Opium War. On 21 August 1841, she was part of the 36-vessel fleet under Admiral Sir
William Parker and
Sir Hugh Gough that attacked
Amoy. During the campaign, she was frequently used for reconnaissance due to her shallow draft, notably scouting the fortifications at
Zhenhai in October 1841. She underwent extensive repairs in Calcutta in May 1843.
Borneo and anti-piracy operations (1844–1847) In 1844, now under Captain Joseph Scott, the
Phlegethon was stationed at Singapore to combat
piracy alongside the
Diana. In July 1844, she joined
Captain Henry Keppel and
James Brooke for an expedition to
Sarawak. • Patusan Attack: The
Phlegethon towed a flotilla of boats up the Batang Lupar river to attack Syarif Sahib, Syarif Mullah and the Skrang Dayak forts. • Brunei Campaign: During the capture of Brunei, 8 July 1846, the vessel suffered a casualty when a 32-pound shot penetrated a paddle box and struck the galley, killing the ship's cook.
Final years and decommissioning (1851–1853) Phlegethon remained in Chinese waters under Captain Niblett until 1851, after which she was deployed to
Moulmein and later
Rangoon for the
Second Anglo-Burmese War. In January 1852, she participated in the bombardment of Burmese fortifications under orders from
Commodore George Lambert. By 1853, the vessel's condition had deteriorated significantly. Under Acting Commander T. H. Hodge, she was found to be structurally unsound and was towed to Calcutta by the
Fire Queen. == Fate ==