The origin of Taps has long been the stuff of legend. One story tells of a young soldier killed during a Civil War battle. His father, a Union officer, found his son’s body with the notes to a new bugle call written on a piece of paper tucked into his pocket. The Union commander, feeling deep sympathy for the father and his dead son, ordered the new bugle call played at the boy’s burial. The new call was so popular that it was soon used at the funeral of all fallen soldiers. The melody became known as Taps.

As lovely and moving as that story is, it is just a story. The true origin of Taps is a little more mundane, but interesting nonetheless.

Bugle Calls
The military has long has a tradition of using bugle calls to issue orders that have to be heard by large groups of soldiers. According to the Military Analysis Network article, “Bugle Calls” these calls were standard and were set down in military manuals, such as Silas Casey’s Tactics.

One of these calls was known as Extinguish Lights (Lights Out), also known as a Tatoo (possibly a corruption of the name of a Dutch army bugle call, Taptoe., which itself may come from the Dutch for “turn off the taps”). The Tatoo was used to recall soldiers from local pubs and tavern at the end of the evening.

Creation of the Modern Taps
According to bugler and bugle call history expert Jari Viilanueva, Union General Daniel Butterfield is credited with composing the final version of Taps.
Read more at Suite101: The Origin of Taps: From Lights Out Call to Funeral Tribute http://us-civil-war.suite101.com/article.cfm/the_origin_of_taps#ixzz0dXJpPxJy