[3] Captain George Grey, the fourth son of Earl Charles Grey, took command of the vessel on 12 August 1835 first sailing to Saint Petersburg, Russia with his sister Lady Louisa, the wife of John Lambton, 1st Earl of Durham and British Ambassador to Russia at the time.
[4] On 19 September, while sailing to St Petersburg, Cleopatra ran aground for several hours on a point of land near Læsø in the Baltic.
[7] Cleopatra set sail for England from St Petersburg on 15 October 1835 arriving at Flamborough Head on 25th.
Her purpose was to transport boys and marines as supernumeraries for other vessels on the South American station.
She left Spithead on 30 November 1835 for Rio de Janeiro, passing Plymouth on 1 December.
Cleopatra made a return journey to St Petersburg in October 1838 taking the new British Ambassador Ulick de Burgh, 1st Marquess of Clanricarde.
During the search a sealed envelope of the Custom House clearance register was opened to verify that the ship was not a slaver.
While in port at Quebec a Cleopatra seaman, Robert Collins, killed the ship's Sergeant of Marines.
The newspaper remarked that the case was unusual in that none of Collins's shipmates spoke up in favour of his character or general conduct.
On 1 August she detained a slave brig, which was sent for adjudication to the Vice-Admiralty Court at British Guiana.
On 25 July she sailed for Mauritius, taking its governor, Major-General Sir William Gumm, and his suite.
By the time she reached Simon's Town only 222 had survived despite being assisted by the crew of Cleopatra, such was the impact of their captivity prior to their rescue.
[17] Cleopatra detained the slave vessel Defensivo on 11 July and both Silveira and Atilla on 29 November.
On 21 March 1844 she was off the coast of Madagascar and anchored about 96 miles (154 km) north of St Augustin's Bay.
In August 1845 Cleopatra began a survey of the attitudes held by the kings and governors of coastal East Africa north of Simon's Town, and from consuls regarding how they saw trade in general progressing.
Cleopatra then sailed on to Johanna, finally returning to Simon's Town Bay on 14 Jan 1846.
Using the ship's boats they rowed up the river and found an American barque, Lucy Penniman of New York, which had sailed there from Rio de Janeiro under her master, Matthew Cooper.
[20] Cleopatra continued her anti-slavery patrols, detaining Constante on 12 July and Improviso on 12 November.
[22] She had had a severe dysentery outbreak among the crew with two dying on the way back from Zanzibar to Simon's Town and 40 on her sick list.
[24] When she arrived in England she was carrying Commander Gooch of HMS Sealark who was not expected to recover.
[28] After completing crewing, loading supplies, and a short sea trial she left for Rio on 15 June.
[30] She arrived in Singapore from Devonport via Rio de Janeiro under Captain Massie on 14 September 1849 and left with HMS Reynard for Labuan and China on 10 October.
On board through this period was Prince Frederick William of Hesse, heir to the Danish throne, who was training as a midshipman.
She remained based there assisting in chasing pirates and sailing variously to Macau, Cumsingmoon, and Manila then East Indies on 30 August, before return to Singapore on 31 October.
Cleopatra was then ordered, along with Semiramis to sail to Labuan, join up with HMS Pluto, and proceed along the coast of Borneo to locate and punish the Sulu pirates responsible for taking Dolphin and killing Robert Burns, a Scottish explorer and ethnologist, and her crew members.
When Cleopatra and SV Semiramis returned, the Naval Commander-in-Chief at Singapore was going to order them to call at Pulo Ubi and Hoonding in Cambodia on their way to China.
In early 1853 the captain, officers, and crew had an obelisk erected in the Hong Kong cemetery to commemorate those lost on the Tunku River expedition.
She remained in Burmese waters till May, participating in the Second Anglo-Burmese War and receiving battle honours.