As I understand it, Memorial Day came out of The Civil War as a holiday to remember what remains the largest number of battlefield deaths for the U.S. military in any war in our history (if we use the term "Americans" then it is Native Americans who lost the most in various ways, but that's another story and deserves another holiday).
It was for many decades known as "Decoration Day" which was changed to Memorial Day later. My mother's mother, who came to live with us when I was a boy after she was widowed, continued to call it "Decoration Day" until she died in the 1950s.
Though there are many veterans in my clan, including my late brothers and me (one of whom is buried in Arlington Cemetery for his service in WWII), we have been fortunate in not having anyone die in war in several generations. But in the extended clan, we have.
So today I'd like to honor the memory of Karina S. Lau, my great-niece Mary's husband's beloved sister (Mary's husband is a military career man still). Karina was one of the early casualties in the Iraq War, and may be the first—certainly among the first—woman to die in that war. She was only twenty years old.
The best way we can honor all our war dead, on all sides of whatever conflict, is to work to make war obsolete. It may be an impossible goal, but at least by working toward that goal we can get closer than ever before (after all, the world has not been as deadly, violent or destructive as it was in WWII since then, so that's some kind of progress).
[You can read one military obit of Karina here.]