A century ago, Christopher Columbus was considered the most glorious explorer in American history. Today, major cities are voting to eliminate the national holiday in his name. What happened?

Source: How did Christopher Columbus become so controversial? – CSMonitor.com

Columbus brought Indians to Europe as slaves, which a church leader in turn sold. How did churchmen get into the business of slavery, which had all but died out during the medieval period? (Serfdom has similarities to slavery but also important differences.) The fact that this happened in Spain, which most keenly felt Muslim influence during the medieval period, should not be overlooked.