A Vice-Admiralty Court was constituted in Freetown, Sierra Leone, so captured slave ships could be legally condemned and processed. This court system mattered because naval seizures needed a legal judgment to be treated as lawful captures and to determine what happened to ships and people found aboard.
The Slave Trade Act received royal assent on 1807-03-25 and made British participation in the Atlantic slave trade illegal. This did not end slavery in the British Empire, but it created the legal foundation for naval enforcement against British slave ships.
In 1808 the Royal Navy organized a dedicated patrol off West Africa to intercept slave ships, later known as the West Africa Squadron (or Preventive Squadron). This marked a shift from law on paper to sustained maritime enforcement along a long coastline and across busy shipping lanes.
On 1810-02-19 Britain and Portugal signed a treaty (often associated with Lord Strangford) that, among other terms, pushed Portugal toward limiting the slave trade. This kind of agreement was important because the squadron’s effectiveness depended on getting legal authority to act against ships sailing under foreign flags.
The Treaty of Ghent, signed on 1814-12-24 to end the War of 1812, included a commitment that Britain and the United States would use their “best endeavours” to abolish the international slave trade. The wording was limited, but it signaled growing diplomatic pressure to treat the trade as illegitimate across borders.
From 1819, Courts of Mixed Commission in Freetown heard cases under bilateral treaties between Britain and other states. These joint courts mattered because they provided internationally recognized procedures for condemning captured slave ships and registering people liberated from them.
On 1829-02-01, HMS Black Joke captured the Spanish slaver El Almirante after a long chase and close fight. High-profile captures like this disrupted slave-trading voyages, produced evidence for court cases, and showed how the squadron relied on fast, lightly armed vessels and aggressive seamanship.
The Slavery Abolition Act (1833) ended slavery in most parts of the British Empire (with a transition period), shifting Britain’s policy from ending trade to ending ownership of enslaved people in many colonies. This strengthened the political and moral case for suppression efforts at sea, even as slavery continued elsewhere.
On 1841-12-20 several European powers signed the Treaty for the Suppression of the African Slave Trade, aiming to coordinate suppression and allow mutual search of merchant ships suspected of slave trading. France declined to ratify, showing the limits of international agreement, but the treaty reflected how suppression was becoming a broader diplomatic project.
The Webster–Ashburton Treaty was signed on 1842-08-09 between the United States and the United Kingdom. It did not grant Britain a broad “right of search” over U.S.-flagged ships, but it supported coordinated action (including naval squadrons) to reduce slave trading under the cover of national flags.
The Slave Trade Act 1843 received royal assent on 1843-08-24 as an effort to make suppression more effective. It updated Britain’s legal tools for prosecution and enforcement, reflecting lessons learned from decades of patrols, seizures, and court cases.
On 1845-08-09 Britain passed the Aberdeen Act (Slave Trade (Brazil) Act 1845), allowing the Royal Navy to stop and seize Brazilian ships suspected of slave trading and bring them to British courts. The law intensified conflict with Brazil, but it also targeted one of the largest remaining Atlantic slave-trading routes.
On 1850-09-04 Brazil enacted the Eusébio de Queirós Law (Law No. 581), making the international slave trade illegal and strengthening repression of trafficking. British naval pressure, including actions enabled by the Aberdeen Act, helped push this major destination market toward enforcement, sharply reducing the trade to Brazil in the following years.
By 1867 the West Africa Squadron’s separate existence ended, after decades of interceptions, legal proceedings, and the landing of “liberated Africans” at ports such as Freetown. Although debate continues about how decisive the squadron was compared with other forces (like changing economics and national laws), its long campaign helped make the Atlantic slave trade harder to operate and less politically defensible.
British naval suppression of the slave trade: the West Africa Squadron (1807–1867)