Bartolomé de las Casas was born in Seville, Spain, in 1484. His father sailed with Columbus on the second voyage to the Americas. Las Casas himself arrived in Hispaniola (present-day Haiti and the Dominican Republic) in 1502, at the age of 18. He participated in the conquest of Cuba in 1512 and, as a reward, was given an encomienda — a grant of indigenous labor that was, in practice, a license to enslave. Las Casas was a priest, a slaveholder, and a participant in the colonial system.
Then he saw what the system was doing. The indigenous population of Hispaniola — estimated at 300,000 to 1,000,000 when Columbus arrived in 1492 — had been reduced to approximately 30,000 by 1514. The people were being worked to death in the mines and on the plantations, subjected to brutal violence, and dying from European diseases at a catastrophic rate. Las Casas, who had been trained as a Dominican priest, was tasked with preparing a sermon. He chose as his text Ecclesiasticus 34: "The bread of the needy is the life of the poor; he that defraudeth them thereof is a man of blood." He freed his own slaves, renounced his encomienda, and began the campaign that would define the rest of his life.
Las Casas's transformation was genuine and profound. He would spend the remaining 52 years of his life fighting for indigenous rights — writing, petitioning the Spanish crown, crossing the Atlantic multiple times, and ultimately facing the Inquisition for his views. He was not a perfect man. He was a man who had been complicit in the system he later fought against, and who carried the moral contradiction of that position for the rest of his life. But his conversion was real, and it produced the most important early critique of European colonialism ever written.