to Spain during Arab domination by North African merchants. By the middle of the 13th century, Christians had reconquered the Iberian peninsula. A section of Seville, which once was a Moorish stronghold, was inhabited by thousands of Africans. Africans became freemen after converting to Christianity, and they lived integrated in Spanish society. African women were highly sought after by Spanish males. Spain's exposure to people of color over the centuries accounted for the positive racial attitudes that prevailed in the New World. Historian Robert Martínez thought it was unsurprising that the first conquistadors intermarried with the native Taíno and later with the African immigrants. The Catholic Church played an instrumental role in preserving the human dignity and working for the social integration of the African man in Puerto Rico. The church insisted that every slave be baptized and converted to the Catholic faith. Church doctrine held that master and slave were equal before the eyes of God, and therefore brothers in Christ with a common moral and religious character. Cruel and unusual punishment of slaves was considered a violation of the fifth commandment. When the gold mines were declared depleted in 1570 and mining came to an end in Puerto Rico, the majority of the white Spanish settlers left the island to seek their fortunes in the richer colonies such as Mexico; the island became a Spanish garrison. The majority of those who stayed behind were either African or mulattoes (of mixed race). By the time Spain reestablished commercial ties with Puerto Rico, the island had a large multiracial population. After the Spanish Crown issued the Royal Decree of Graces of 1815, it attracted many European immigrants, in effect "whitening" the island into the 1850s. But, the new arrivals also intermarried with native islanders, and added to the multiracial population. They also identified with the island, rather than simply with the rulers. Two Puerto Rican writers have written about racism; Abelardo Díaz Alfaro (1916–1999) and Luis Palés Matos (1898–1959), who was credited with creating the poetry genre known as Afro-Antillano. Spanish–American War The Treaty of Paris of 1898 settled the Spanish–American War, which ended the centuries-long Spanish control over Puerto Rico. Like with other former Spanish colonies, it now belonged to the United States. With the United States control over the island's institutions also came a reduction of the natives' political participation. In effect, the U.S. military government defeated the