Anti-Slavery Convention it held in London in 1840. Moldavia and Wallachia In the principalities of Wallachia and Moldavia, the government held slavery of the Roma (often referred to as Gypsies) as legal at the beginning of the 19th century. The progressive pro-European and anti-Ottoman movement, which gradually gained power in the two principalities, also worked to abolish that slavery. Between 1843 and 1855, the principalities emancipated all of the 250,000 enslaved Roma people. In the Americas Bartolomé de las Casas was a 16th-century Spanish Dominican priest, the first resident Bishop of Chiapas (Central America, today Mexico). As a settler in the New World he witnessed and opposed the poor treatment and virtual slavery of the Native Americans by the Spanish colonists, under the encomienda system. He advocated before King Charles V, Holy Roman Emperor on behalf of rights for the natives. Las Casas for 20 years worked to get African slaves imported to replace natives; African slavery was everywhere and no one talked of ridding the New World of it, though France had abolished slavery in France itself and there was talk in other countries about doing the same. In fact, from a purely economic point of view Africans were better slaves, stronger and healthier, because the "Middle Passage" had selected for these traits. However, Las Casas had a late change of heart, and became an advocate for the Africans in the colonies. His book, A Short Account of the Destruction of the Indies, contributed to Spanish passage of colonial legislation known as the New Laws of 1542, which abolished native slavery for the first time in European colonial history. It ultimately led to the Valladolid debate, the first European debate about the rights of colonized people. Latin America During the early 19th century, slavery expanded rapidly in Brazil, Cuba, and the United States, while at the same time the new republics of mainland Spanish America became committed to the gradual abolition of slavery. During the Spanish American wars for independence (1810–1826), slavery was abolished in most of Latin America, though it continued until 1873 in Puerto Rico, 1886 in Cuba, and 1888 in Brazil (where it was abolished by the Lei Áurea, the "Golden Law"). Chile declared freedom of wombs in 1811, followed by the United Provinces of the River Plate in 1813, Colombia and Venezuela in 1821, but without abolishing slavery completely. While Chile abolished slavery in 1823,