President Obama lays wreath at the Tomb of the Unknown Soldier

President Obama, back in Washington after his surprise trip to visit troops in Afghanistan, appeared at Arlington National Cemetery this morning to lay a wreath at the Tomb of the Unknown Soldier.

The more than 220,000 flags have been placed in front of the graves at Arlington, a tradition dating back to the first Decoration Day held in 1868 to honor those killed during the Civil War. After WWI, Decoration Day was expanded to honor men and women killed in the U.S. armed services in all conflicts.