This little article is from The San Fernando Valley Folklore Society's Urban Legends page, an invaluable resource, as I get junk urban legend email all the time. (The URL is www.snopes.com) - Jonah
"Tapping the Admirable" The urban legend in question is one about how a father and son, fighting on opposite sides, meet for one last time on a Civil War battlefield. Found in the dying boy's pocket is the melody now known as 'Taps.'
The link that explains this little tale is here, until the people at Snopes decide to change addresses again and render this link invalid!