No one knows where, exactly, Memorial Day began. The question of when is easier to answer -- it started with the Civil War, with unplanned and unprompted gestures of respect for the fallen soldiers on both sides of the Mason Dixon line.
Decoration Day, it was called then, and the families and loved ones of the fallen would do just that, decorate the soldiers' graves with flags and flowers. It all became official in May of 1868, and the first Memorial Day ceremony took place at Arlington National Cemetery on May 30. So many wars and so many lives later, the same ceremony is taking place there today.
What can you do to honor the war dead? Hang a flag, attend a ceremony, or read about the history of the day. You can visit the LA Times' remarkable online memorial (the comments are so moving) to Californians who have perished in the wars in Iraq and Afghanistan; visit the Washington Post's memorial, which covers all 50 states; or read about the volunteers at Riverside National Cemetery reciting aloud the names of all 148,000 military veterans and soldiers buried there. Here's the story in the local paper, the Press Enterprise, and here's the piece in the NY Times.
That's my dad in the photo, the guy on the right, a 19-year-old in the French infantry, somewhere in Germany in 1945.