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Memorial Day was originally established to honor military personnel who died in the Civil War. Since that time, its purpose has expanded to include honoring the casualties from other U.S. wars including, but not limited to, World War I, World War II, the Korean War, the Vietnam Conflict, Operation Desert Shield/Desert Storm, Operation Iraqi Freedom, and others. Red poppies are known as a symbol of remembrance, and it's a tradition to wear them to honor those who died in war.