President Barack Obama sent a wreath Monday to a memorial for soldiers who fought on the side of slavery during the Civil War, continuing a 90-year-old Memorial Day tradition despite being urged by historians to “break this chain of racism.” The first black U.S. president also started a new tradition by sending a wreath to the African American Civil War Memorial in Washington honoring the 200,000 black soldiers who fought for Union forces in America’s bloodiest conflict. “We ask you to break this chain of racism stretching back to Woodrow Wilson and not send a wreath or other token of...