1772: Lord Mansfield’s decision: Slaves become free upon entering the British Isles, thus making it illegal to repossess fugitive slaves.

1780: Pennsylvania passes act for the gradual abolition of slavery.

1783: The Society of Friends (England) forms an antislavery association for the relief of slaves and the discouragement of the slave trade.

1783: Massachusetts declares slavery illegal.

1787: The Abolition Society of Samuel Wilberforce founds Freetown, Sierra Leone, as a home for liberated slaves.

1788: Dolben Act regulates British slave trade.

1789: British Parliament debates the abolition of the slave trade.

1791: Slaves rebel on the French island of Saint Domingue. The last European forces are evacuated in 1798, and the independent, black government of Haiti is established.

1791: First U.S. measures abolishing the slave trade.

1792: Denmark declares its intention to abolish the slave trade.

1794: French Republic abolishes slavery (subsequently revoked by Napoleon, 1802).

1799: The Church Missionary Society (England) is founded to pursue humanitarian aims in Africa, including the fight against the slave trade.

1803: Denmark abolishes the slave trade.

1804: Haiti recognized as independent country, abolishes slavery.

1805: British Order-in-Council restricts the import of slaves into colonies captured from France and Holland (Le., since 1802).

1806: Act of Parliament prohibits British participation in the slave trade to foreign territories, effectively outlawing two-thirds of the British trade.

1807: The Abolition Act prohibits all British subjects from participation in the slave trade as of January 1, 1808. A naval squadron that eventually reaches one-sixth of the total strength of the Royal Navy is dispatched to blockade the West African coast.

1808: Sierra Leone becomes a British colony and a center of antislave trade activities.

1808: The United States abolishes slave trade.

1810: Anglo-Portuguese treaty whereby Portugal agrees to restrict its slave trade to its own colonies.

1811: Parliament strengthens the Abolition Act by declaring that British subjects engaged in the slave trade are to be considered pirates.

1813: Anglo-Swedish treaty whereby Sweden outlaws the slave trade.

1814: The Treaty of Paris: France and Britain agree that the slave trade is “repugnant to the principles of natural justice.” France agrees to limit its trade to its own colonies and to abolish the trade in five years.

1814: Anglo-Netherlands treaty whereby the latter outlaws the slave trade.

1814: Anglo-Spanish treaty whereby Spain limits its slave trade to its own colonies and prohibits the trade north of the equator after 1817 and south of the equator after 1820 in return for £400,000 in compensation.

1815: Anglo-Portuguese treaty whereby Portugal agrees to limit its slave trade to its possessions south of the equator. In return, Britain waives Portugal’s war debt of £450,000.

1815: Congress of Vienna: Britain, France, Prussia, Russia, Portugal, Spain, Austria, and Sweden condemn the slave trade as “repugnant to the principles of humanity and universal morality.”

1817: British convention with Portugal limits the Portuguese slave trade in East Africa to an area from Cape Delgado to the Bay of Lourenco Marques. Portugal also concedes visit-and-search rights on Portuguese ships suspected of violating this and other agreements.

1817: British treaty with Imerina prohibits the export of slaves from Madagascar in return for compensation of £2,000 per year. Imerina outlaws slave raiding in the Comoro Islands on penalty of being reduced to slavery.

1817: Anglo-Spanish treaty grants Britain the right to detain Spanish ships.

1818: France outlaws the slave trade.

1820: British treaty with Imerina is extended.

1820–5: Slavery is outlawed throughout the newly independent Spanish countries of Latin America.

1821: Slave imports into Cuba become illegal, although the effect is minimal.

1822: The American Colonization Society establishes Liberia as a home for liberated American slaves.

1822: Moresby Treaty between Britain and Muscat prohibits the export of slaves by Europeans in East Africa and establishes a British observer at Zanzibar. Britain recognizes Omani claims in East Africa, including the existence of slavery.

1823: A third treaty with Imerina whereby Britain is authorized to seize slavers; it also provides for the resettlement of liberated slaves.

1823: Society for the Mitigation and Gradual Abolition of Slavery throughout the British Dominions is founded.

1824: Establishment of British protectorate over Mombasa with intention to restrict slave trade; protectorate terminates in 1826 under Zanzibar pressure.

1825: Hugh Clapperton and Dixon Denham negotiate treaties with the Sokoto Caliphate and Borno to end slave exports in return for trade in European goods.

1826: Newly independent Brazil accepts Portugal’s treaty obligations with Britain and promises to abolish the slave trade in three years.

1829: Mexico abolishes slavery.

1831: Anglo-French treaty provides for mutual, limited right to search vessels suspected of carrying slaves.

1831: Brazil officially abolishes slave trade.

1833: Britain emancipates slaves in its West Indian colonies, South Africa, and Mauritius, with compensation to slave owners; emancipation takes effect on August 1, 1834, although a system of apprenticeship lasts for four years in some colonies.

1835: Anglo-Spanish treaty for condemnation of slave ships.

1836: Portugal abolishes slave trade.

1838: Thomas F. Buxton launches a campaign against slavery, advocating free trade and the colonization of the African interior with freed, Christian slaves. Buxton’s efforts result in the strengthening of the British naval squadron off the West African coast and the signing of antislave trade treaties with African states.

1839: Convention between Oman (Zanzibar) and Britain, which extends rights of search and seizure.

1839: Joseph Sturge founds the British Anti-Slavery Society.

1839: Buxton establishes the African Civilization Society as part of his abolition campaign.

1841: The British Aborigines’ Protection Society is founded in England.

1841: Britain, France, Austria, Prussia, and Russia agree to extend rights of search and seizure to halt the slave trade, although France refuses to ratify the treaty.

1842: Webster-Ashburton Treaty: Britain and the United States agree to maintain a naval force of at least eighty guns off the African coast as part of a joint commitment to suppress the slave trade.

1843: The legal status of slavery is abolished in India and elsewhere, although slaves are not emancipated.

1843: France initiates or “free labor” emigration in its colonial possessions to circumvent antislavery treaties.

1844: Britain signs treaty with Sultanate of Anjouin (Comoro Islands) to prevent French recruitment of labor.

1845: Anglo-French treaty: Both powers agree to maintain at least twenty-six cruisers off the African coast as an antislave-trade force; rights of search and seizure are abrogated. France does not adhere to the treaty, which is allowed to expire after ten years.

1845: British treaty with Oman (Zanzibar): Slave trade is restricted to Oman’s possessions in Arabia and East Africa; Britain secures the right of search and seizure.

1846: Tunisia abolishes the slave trade to gain British support against the Ottoman Empire.

1847: The Ottoman Empire prohibits the slave trade in the Persian Gulf and closes public slave markets in Constantinople.

1847: Liberia becomes an independent republic.

1848: Persia bans the maritime slave trade.

1848: France emancipates slaves in its colonies.

1849: French preventative squadron off the West African coast is reduced.

1849: France establishes Libreville, Gabon, as a settlement for freed slaves.

1849: Establishment of British consuls and agents in West Africa to supervise treaty obligations, including antislave trade provisions. Royal Navy squadron is strengthened.

1850: Brazil enforces slave trade abolition.

1851: Britain deposes the ruler of Lagos for his refusal to take action against the slave trade. Antislave trade treaties are signed with Lagos, Dahomey, Porto Novo, Badagry, and Abeokuta.

1851: Anglo-Persian treaty grants Britain right of search and seizure.

1854: Portugal decrees that slaves in its territories are .

1854: Egypt bans public slave markets, although trade continues in private.

1854: The Ottoman Empire prohibits the white slave trade.

1855: First of several treaties with principalities on the Red Sea coast that grant right of search and seizure to Britain; official appointed to Berbera.

1857: The Ottoman Empire prohibits the slave trade in its domains, although the decree is not enforced.

1859: France abolishes the system, although enforcement is not strict.

1861: The Canning Award: Zanzibar and Oman are separated, thereby setting the stage for the further suppression of the slave trade in the Indian Ocean.

1862: Treaty of Washington: The United States grants Britain the right of search and seizure.

1865: Thirteenth Amendment to the U.S. Constitution abolishes slavery.

1865: British treaty with Imerina whereby Imerina prohibits the importation of slaves.

1867: Cuba ends slave trade.

1869: The Royal Navy begins intensive patrolling against Arab slave trade.

1869: Portugal abolishes slavery.

1870: Ownership of slaves becomes illegal in India.

1873: Kirk-Barghash treaty: Zanzibar bans public slave markets and promises to protect liberated slaves.

1874: Proclamation for the emancipation of slaves on the Gold Coast, following the British defeat of Asante.

1875: British treaty with Tunisia confirming abolition of slavery and the slave trade. Annexation subsequently revoked.

1876: France incorporates Walo and Dimar into Senegal, thereby abolishing slavery.

1876: British Royal Commission investigates the treatment of fugitive slaves in East Africa but opposes asylum for fugitives except in cases of physical danger.

1877: Anglo-Egyptian treaty prohibits the import, export, and transit of slaves in Egypt; domestic slavery to be outlawed by 1884 in Egypt and 1889 in the Nilotic Sudan.

1877: Britain undertakes to reorganize the Zanzibar army to combat the slave trade in the interior.

1877: Imerina declares all slaves from Mozambique free.

1878: Portugal abolishes legal status of slavery.

1880: Anglo-Ottoman Convention reaffirms the prohibition of the slave trade and grants Britain rights of search.

1882: Colonel Charles Gordon, seeking to check the Mahdist rebellion, rescinds the law banning the slave trade in the Nilotic Sudan.

1883: Morocco rejects the “friendly appeal” of the British Foreign Office for the abolition of slavery.

1883: The African Department of the British Foreign Office replaces the Slave Trade Department as the era of “moral temporizing” ends.

1883: Britain assigns four traveling consuls to East Africa to replace naval action against the slave trade.

1884: France and Britain forbid employees and in Morocco to own slaves.

1884: British treaty with Ethiopia grants Ethiopia access to the Red Sea through Massawa on a condition that slave trade ends in the interior.

1885: Berlin Conference: Britain, France, Austria, Germany, Russia, Spain, Portugal, Holland, Belgium, Italy, the Ottoman Empire, Sweden, Denmark, and the United States agree to “help in suppressing slavery,” although no direct measures are taken against the slave trade in Africa.

1888: Brazil becomes the last American country to abolish slavery.

1888: Cardinal Lavigerie inaugurates a campaign against the slave trade in central Africa, thereby revitalizing the humanitarian cause in Britain and Europe.

1888: Imperial British East Africa Company pays more than £3,000 compensation for 1,400 fugitive slaves at the CMS mission stations near Mombasa.

1888: Germany, Britain, and Italy blockade the coast of Zanzibar, ostensibly to suppress the slave trade.

1889: Zanzibar grants the British and Germans perpetual right of search, decrees that new slaves entering its domains after November 1, 1889 shall be free, and provides for the emancipation of all slave children born after January 1, 1890.

1889: Brussels Conference: The participants of the Berlin Conference, plus Persia, Zanzibar, and the Congo Free State, condemn slavery and the slave trade. Bureaux are established in Brussels and Zanzibar to collate and disseminate information on the slave trade.

1892: Convention between France and the independent states of Senegal in which slaves are recognized as servants; French courts grant certificates of liberty to those slaves buying their freedom.

1893: Renwell Rodd’s report to the British parliament recommending the gradual abolition of the slave trade in East Africa.

1894: British emancipation ordinance in the Gambia for gradual termination of slavery; slaves to be free at death of master or payment of £10 (adults) or £5 (children).

1896: Legal status of slavery abolished in Sierra Leone.

1897: Legal status of slavery abolished in Zanzibar.

1897: Slavery is abolished in Madagascar, following the French invasion of Imerina in 1895.

1899: Joint deputation of Quakers and the Anti-Slavery Society meets with the British Under-Secretary for Foreign Affairs to demand emancipation of slaves in Africa.

1900: Britain abolishes the legal status of slavery in the occupied parts of Nigeria with the intention of extending the decree throughout Nigeria.

1909: Institution of slavery abolished in Zanzibar.

1919: Treaty of Saint Germain-en-Laye: The Allies limit (but do not prohibit) the slave trade in Africa. The signatories pledge to “secure the complete suppression of slavery in all its forms and of the slave trade by land and sea.”

1926: Forty-four countries ratify the slavery convention of the League of Nations.

1928: Institution of slavery is abolished in Sierra Leone.

1930: League of Nations’ prohibition of slavery is extended to include all forms of forced labor.

1936: League of Nations establishes a Permanent Advisory Committee on the suppression of the slave trade.

1942: Legal status of slavery is abolished in Ethiopia.

1962: Saudi Arabia becomes the last country to abolish the legal status of slavery.