Extensive slavery timeline from years 1102 - 1982.
It should be noted that many of these changes were reversed in practice over the succeeding centuries.
1102 Trade in slaves and serfdom ruled illegal in London: Council of London
1117 Slavery abolished in
1200 Slavery virtually disappears in Japan; it was never widespread and mostly involved captives taken in civil wars.
1214 The Statute of the Town of Korčula (Croatia) abolishes slavery.
1274 Landslova (Land's Law) in Norway mentions only former slaves, which indicates that slavery was abolished in Norway
1315 Louis X, king of France, publishes a decree proclaiming that "France" signifies freedom and that any slave setting foot on the French ground should be freed
1335 Sweden (including Finland at the time) makes slavery illegal.
1416 Republic of Ragusa (modern day Dubrovnik; Croatia) abolished slavery and slave trading
1569 An English court case involving Cartwright who had bought a slave from Russia ruled that English law could not recognize slavery.
1588 The Polish–Lithuanian Commonwealth abolishes slavery
1595 A law is passed in Portugal banning the selling and buying of Chinese slaves.
16th century Japan Toyotomi Hideyoshi outlaws export of Japanese as slaves by Portuguese traders
1600 Last villein dies in EnglandFebruary 19, 1624, The King of Portugal forbids the enslavement of Chinese of either sex.
1652 Slavery abolished in Providence Plantations.
1683 The Spanish crown abolishes slavery in Chile
1701 The Lord Chief Justice rules that a slave became free as soon as he arrived in England.
1723 Russia abolishes outright slavery but retains serfdom.
1761 12 February, Portugal abolishes slavery in mainland Portugal and in Portuguese possessions in India through a decree by the Marquis of Pombal.
1772 The Somersett's case held that no slave could be forcibly removed from Britain. This case was generally taken at the time to have decided that the condition of slavery did not exist under English law in England and Wales, and emancipated the remaining ten to fourteen thousand slaves or possible slaves in England and Wales, who were mostly domestic servants.
1777 Slavery abolished in Madeira, Portugal
1777 Constitution of the Vermont Republic bans slavery.
1780 Pennsylvania passes An Act for the Gradual Abolition of Slavery, freeing future children of slaves. Those born prior to the Act remain enslaved-for-life. The Act becomes a model for other Northern states.
1783 Russia abolishes slavery in Crimean Khanate
1783 Massachusetts rules slavery illegal based on 1780 constitution. All slaves immediately freed.
1783 Bukovina: Joseph II, Holy Roman Emperor issued an order abolishing slavery on 19 June 1783 in Czernowitz
1783 New Hampshire begins a gradual abolition of slavery, freeing future children of slaves, and all slaves in (Year).
1784 Connecticut begins a gradual abolititon of slavery, freeing future children of slaves, and all slaves in [year].
1784 Rhode Island begins a gradual abolition of slavery, freeing future children of slaves, and all slaves in [year].
1787 Sierra Leone founded by Britain as colony for emancipated slaves
1787 Society for the Abolition of the Slave Trade founded in Britain
1788 Sir William Dolben's Act regulating the conditions on British slave ships enacted
1792 Denmark-Norway declares transatlantic slave trade illegal after 1803 (though slavery continues to 1848)
1793 Upper Canada, abolishes import of slaves by Act Against Slavery
1794 French First Republic abolishes slavery
1799 New York State passes gradual emancipation act freeing future children of slaves, and all slaves in 1827.
1799 in Scotland, by an act of the Parliament of Great Britain—the 'Colliers (Scotland) Act 1799' (39 Geo III c. 56) ended the legal slavery of Scottish coal miners that had been established by the Parliament of Scotland in 1606. The Colliers and Salters (Scotland) Act 1775 (15 Geo III c. 28) was originally intended to accomplish this, but it had been only partially effective.
1802 The First Consul Napoleon re-introduces slavery on French colonies growing sugarcane.
1803 Denmark-Norway abolishes transatlantic slave trade on 1 January 1803
1803 Lower Canada abolishes slavery
1804 New Jersey begins a gradual abolition of slavery, freeing future children of slaves. Those born prior to the Act remain enslaved-for-life; all the Northern states have now abolished slavery
1804 Haiti declares independence and abolishes slavery
1805 Bill for Abolition passed in Commons, rejected in the House of Lords.
1807 25 March Abolition of the Slave Trade Act: slave trading abolished in British Empire. Captains fined £120 per slave transported.
1807 British begin patrols of African coast to arrest slaving vessels. West Africa Squadron (Royal Navy) established to suppress slave trading; by 1865, nearly 150,000 people freed by anti-slavery operations
1807 Abolition of serfdom in Prussia through the Stein-Hardenberg Reforms.
1808 United States—import and export of slaves prohibited after 1 Jan.
1810 Mexico: Miguel Hidalgo y Costilla declared slavery abolished, but it wasn't official until Independence War finished
1811 Slave trading made a felony in the British Empire punishable by transportation for British subjects and foreigners.
1811 Spain abolishes slavery at home and in all colonies except Cuba, Puerto Rico, and Santo Domingo
1811 Chile: The First National Congress approves a proposal drafted by Manuel de Salas that declares the Freedom of wombs, which sets free the sons of slaves born on Chilean territory, no matter the conditions of the parents; it prohibited the slave trade and recognized as freedmen those who, passing in transit through Chilean territory, stayed there for six months.
1813 Argentina: the Law of Wombs was passed on February 2, by the Assembly of Year XIII. The law stated that those born after January 31, 1813 would be granted freedom when contracting matrimony, or on their 16th birthday for women and 20th for men, and upon their manumission would be given land and tools to work it. In 1853, slavery was completely abolished.
1814 Uruguay, before its independence, declares all those born of slaves in their territories are free from that day forward.
1814 Dutch outlaw slave trade.
1815 British pay Portugal £750,000 to cease their trade north of the Equator
1815 Congress of Vienna. 8 Victorious powers declared their opposition to slavery
1816 Serfdom abolished in Estonia.
1817 Serfdom abolished in Courland.
1817 Spain paid £400,000 by British to cease trade to Cuba, Puerto Rico, and Santo Domingo
1817 New York State sets a date of July 4, 1827 to free all its slaves.
1818 Treaty between Britain and Spain to abolish slave trade
1818 Treaty between Britain and Portugal to abolish slave trade
1818 France and Netherlands abolish slave trading
1819 Treaty between Britain and Netherlands to abolish slave trade
1819 Serfdom abolished in Livonia.
1820 Compromise of 1820 in U.S. prohibits slavery north of a line (36°30')
1821 Gran Colombia (Ecuador, Colombia, Venezuela, Panama) declares free the sons and daughters born to slave mothers, sets up program for compensated emancipation
1822 Liberia founded by American Colonization Society (USA) as a colony for emancipated slaves.
1822 Greece abolishes slavery
1823 Chile abolishes slavery
1824 The Federal Republic of Central America abolishes slavery.
1825 Uruguay declares independence from Brazil and prohibits the traffic of slaves from foreign countries.
1827 Treaty between Britain and Sweden to abolish slave trade
1827 New York State abolishes slavery. Children born between 1799 and 1827 are indentured until age 25 (females) or age 28 (males).
1829 Mexico officially abolishes slavery
1830 The first Constitution of Uruguay declares the abolition of slavery.
1831 Bolivia abolishes slavery
1833 The British Slavery Abolition Act 1833 comes into force, abolishing slavery throughout most of the British Empire. The exceptions being territories controlled by the Honourable East India Company and Ceylon which were liberated in 1843 when they became part of the British Empire. Legally frees 700,000 in West Indies, 20,000 in Mauritius, 40,000 in South Africa.
1835 Treaty between Britain and France to abolish slave trade
1835 Treaty between Britain and Denmark to abolish slave trade
1836 Portugal abolishes transatlantic slave trade
1838 1 August – enslaved men, women and children in the British Empire finally became free after a period of forced apprenticeship following the passing of the Slavery Abolition Act in 1833
1839 British and Foreign Anti-Slavery Society founded, now called Anti-Slavery International
1839 Indian indenture system made illegal (reversed in 1842)
1840 Treaty between Britain and Venezuela to abolish slave trade
1841 Quintuple Treaty is signed; Britain, France, Russia, Prussia, and Austria agree to suppress slave trade
1842 Treaty between Britain and Portugal to extend the enforcement of the ban on slave trade to Portuguese ships sailing south of the Equator.
1843 Honourable East India Company becomes increasingly controlled by Britain and abolishes slavery in India by the Indian Slavery Act V. of 1843.
1843 Treaty between Britain and Uruguay to suppress slave trade
1843 Treaty between Britain and Mexico to suppress slave trade
1843 Treaty between Britain and Chile to suppress slave trade
1843 Treaty between Britain and Bolivia to abolish slave trade
1845 36 British Royal Navy ships are assigned to the Anti-Slavery Squadron, making it one of the largest fleets in the world.
1846 Tunisia abolishes slavery
1847 Ottoman Empire abolishes slave trade from Africa.
1847 Sweden abolishes slavery
1847 Slavery ends in Pennsylvania. Those born before 1780 (fewer than 100 in 1840 Census) are freed.
1848 Denmark abolishes slavery
1848 Slavery abolished in all French and Danish colonies
1848 France founds Gabon for settlement of emancipated slaves.
1848 Treaty between Britain and Muscat to suppress slave trade
1849 Treaty between Britain and Persian Gulf states to suppress slave trade
1850 United States: Fugitive Slave Law of 1850 requires return of escaped slaves
1851 New Granada (Colombia) abolishes slavery
1852 The Hawaiian Kingdom abolishes kauwa system of serfdom.
1853 Argentina abolishes slavery when promulgating the 1853 Constitution
1854 Peru abolishes slavery
1854 Venezuela abolishes slavery
1855 Moldavia partially abolishes slavery.
1856 Wallachia partially abolishes slavery.
1860 Indenture system abolished within British occupied India.
1861 Russia frees its serfs in the Emancipation reform of 1861.
1862 Treaty between United States and Britain for the suppression of the slave trade (African Slave Trade Treaty Act).
1862 Cuba abolishes slave trade
1863 Slavery abolished in Dutch colonies.
1863 United States: Emancipation Proclamation declares those slaves in Confederate-controlled areas to be freed. Most slaves in "border states" are freed by state action; separate law frees the slaves in Washington, D.C.
1865 United States abolishes slavery with the Thirteenth Amendment to the United States Constitution; about 40,000 remaining slaves are affected.
1869 Portugal abolishes slavery in the African colonies
1870 U.S. abolishes slavery in the Department of Alaska after purchasing it from Russia in 1867
1871 Brazil declares free the sons and daughters born to slave mothers after 28 September 1871.
1873 Slavery abolished in Puerto Rico
1873 Treaty between Britain and Zanzibar and Madagascar to suppress slave trade
1874 Britain abolishes slavery in the Gold Coast (now Ghana) following its annexation in 1874 (after Third Anglo-Asante War).
1879 Bulgaria abolishes slavery (note: the slavery was abolished with the first constitution of the renewed Bulgarian state)
1882 Ottoman firman abolishes all forms of slavery, white or black.
1885 Brazil passes Sexagenarian Law freeing all slaves over the age of 60.
1886 Slavery abolished in Cuba
1888 Brazil passes Golden Law, abolishing slavery without indemnities to slave owners or aid to newly freed slaves.
1890 Brussels Act – Treaty granting anti-slavery powers the right to stop and search ships for slaves
1894 Korea abolishes slavery
1896 France abolishes slavery in Madagascar
1897 Zanzibar abolishes slavery following its becoming a British protectorate
1906 China formally abolishes slavery and the law became effective on 31 January 1910, when all adult slaves were converted into hired labourers and the young were freed upon reaching age 25.
1912 Siam (Thailand), formally abolishes all slavery. The act of selling a person into slavery was abolished in 1897 but slavery itself was not outlawed at that time.
1921 Nepal abolishes slavery
1923 Afghanistan abolishes slavery
1922 Morocco abolishes slavery
1924 Iraq abolishes slavery
1924 League of Nations Temporary Slavery Commission
1926 Slavery Convention. Bound all signatories to end slavery Convention to Suppress the Slave Trade and Slavery (25 September 1926)
1928 Iran abolishes slavery
1928 Domestic slavery practiced by local African elites abolished in Sierra Leone (ironically established as a place for freed slaves). A study found practices of domestic slavery still widespread in rural areas in the 1970s.
1935 Italian General Emilio De Bono proclaims slavery to be abolished in the Ethiopian Empire
1936 Britain abolishes slavery in Northern Nigeria
1942 Ethiopian Empire abolishes slavery
1945 In the subsequent defeat of Nazi Germany and Japan, workcamps for slave labor (primarily Jewish encampments in Nazi Germany and colonists in Japanese-dominated lands) were gradually closed by the liberators.
1946 Fritz Sauckel, procurer of slave labor for Nazi Germany, convicted at the Nuremberg trials and executed as war criminal.
1948 UN Article 4 of the Declaration of Human Rights bans slavery globally
1952 Qatar abolishes slavery
1959 Slavery in Tibet is abolished by China after the Dalai Lama flees.
1960 Niger abolishes slavery
1962 Saudi Arabia abolishes slavery
1962 Yemen abolishes slavery
1963 United Arab Emirates abolishes slavery
1970 Oman abolishes slavery
1981 Mauritania abolishes slavery
While now illegal everywhere, slavery or practices akin to it continue today in many countries throughout the world.
Slavery Timeline source: Wikipedia