Short answers, pulled from the story.
France was the first country to fully outlaw slavery in 1315, when King Louis X decreed that any enslaved person setting foot on French soil must be freed. However, France continued to permit slavery in its overseas colonies. The first country to abolish and punish slavery for indigenous people was Spain, with the New Laws of 1542.
Lord Mansfield's judgment of the 22nd of June 1772 declared that slavery could not exist under English common law because no legislation had ever established it in England. The ruling freed the enslaved man James Somersett, who had been captured and imprisoned on a ship bound for Jamaica. The decision helped launch the British movement to abolish slavery.
The Slave Trade Act was passed on the 25th of March 1807, making the slave trade illegal throughout the British Empire. Slavery itself was not abolished until the Slavery Abolition Act 1833, passed on the 28th of August 1833, which freed enslaved people throughout the British Empire by 1838.
Haiti is the only country to have liberated itself from slavery through a revolution by enslaved people. The rebellion began in the French colony of Saint-Domingue in 1791, led by figures including Toussaint L'Ouverture and Jean-Jacques Dessalines. Victory at the decisive Battle of Vertières forced the French out, and Haiti declared independence in 1804.
On the 1st of January 1863, Abraham Lincoln issued the Emancipation Proclamation, an executive order that changed the legal status of three million enslaved people in Confederate states from enslaved to free. Slavery was formally ended throughout the United States by the 13th Amendment, ratified in December 1865.
Mauritania issued a presidential decree abolishing slavery in 1981, making it the most recent country to formally abolish the institution. Despite this, illegal forced labor and human trafficking continue to affect tens of millions of people globally, according to International Labour Organization estimates.