The British Navy in the post-Napoleonic era was the most powerful navy in the world. As the Royal Navy notes in the historical timeline on its website, "for the century after the Battle of Waterloo the United Kingdom was supreme upon the world's oceans" ('1815-1914 Historic Periods: Maintaining Naval Supremacy'). His Majesty's Ships Phaeton and Conqueror, built in the late 18th and early 19th centuries, both took part in engagements during the Napoleonic Wars (according to the British National Archives, the Conqueror was at the battle of Trafalgar in 1805), while the Tees was completed in 1817, two years after Napoleon surrendered and was exiled to St. Helena ('Trafalgar Ancestors'). At the time the logs were kept, HMS Phaeton was captained by Francis Stanfell, the HMS Tees was captained by George Rennie, and the HMS Conqueror was captained by James Wallis. According to the logs and to the dealer's notes that came with them, the three ships were in the waters around St. Helena and the African coast during the years 1817-1819, and their mission was to disrupt the transatlantic slave trade. As noted by the British National Archives in a background document on abolition, the slave trade in the United Kingdom was abolished in 1807, and "under an 1817 treaty with Spain to abolish the slave trade, naval ships and other officials of both nations could seize any Spanish or British ships believed to be involved in the illegal trade in slaves" ('Abolition'). In spite of these efforts, the actual practice of slavery in Britain's colonies was not outlawed until 1833.