I was trying to figure out which one. It was France.
1863: In the United States, Abraham Lincoln signs the Emancipation Proclamation which declared slaves in Confederate-controlled areas to be freed. Most slaves in “border states” are freed by state action; separate law freed the slaves in Washington, D.C.
1865: December: U.S. abolishes slavery with the Thirteenth Amendment to the United States Constitution; about 40,000 remaining slaves are affected.[45]
1866: Slavery abolished in Indian Territory (now Oklahoma).[46]
1869: Portugal abolishes slavery in the African colonies
1871: Brazil Rio Branco Law declares free the sons and daughters born to slave mothers after 28 September 1871.[47]
1873: Slavery abolished in Puerto Rico
1873: Treaty between Britain and Zanzibar and Madagascar to suppress slave trade [33]
1874: Britain abolishes slavery in the Gold Coast (now Ghana), following its annexation in 1874.[48]
1882: Ottoman firman abolishes all forms of slavery, white or black.[49]
1885: Brazil passes Sexagenarian Law freeing all slaves over the age of 60.
1886: Slavery abolished in Cuba[17]
1888: Brazil passes Golden Law, abolishing slavery without indemnities to slaveowners or aid to newly freed slaves.[50]
1890: Brussels Conference Act – a collection of anti-slavery measures to put an end to the slave trade on land and sea especially in the Congo Basin, the Ottoman Empire and the East African coast
1894: Korea officially abolishes slavery, but it survives in practice until 1930.[51]
——> 1896: France abolishes slavery in Madagascar
1897: Zanzibar abolishes slavery[52] following its becoming a British protectorate
1902: Ethiopian Empire abolishes slavery (though it was not legally and officially abolished by Emperor Haile Selassie in 1942)
1906: China formally abolishes slavery effective 31 January 1910, when all adult slaves were converted into hired labourers and the young were freed upon reaching age 25.[14]
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.[53]
1921: Nepal abolishes slavery[54][55]
1922: Morocco abolishes slavery [56]
1923: Afghanistan abolishes slavery[57]
1924: Iraq abolishes slavery
1924: League of Nations Temporary Slavery Commission
1926, 25 September: Convention to Suppress the Slave Trade and Slaverybound all signatories to end slavery.
1928: Iran abolishes slavery[58]
1928: Domestic slavery practised by local African elites abolished in Sierra Leone[59] Though 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[60]
1936: Britain abolishes slavery in Northern Nigeria[61]
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[62]
1952: Qatar abolishes slavery
1959: Slavery in Tibet is abolished by China after the Dalai Lama flees.
1960: Niger abolishes slavery (though it was not made illegal until 2003)[63]
1962: Saudi Arabia abolishes slavery
1962: Yemen abolishes slavery
1963: United Arab Emirates abolishes slavery
1970: Oman abolishes slavery
1981: Mauritania abolishes slavery
BTW- What the heck is Muscat?
True enough. However, Madagascar was not part of the French Empire till 1896, so you can't really blame slavery there on the French before then. :)
Muscat is the capital of Oman. In old books you'll often see "Muscat and Oman" referred to.