This is a bugle call played by military forces to wake up the soldiers at the start of the day. Shorter alternative calls used by some forces include The First Post, Charlie Reveille, Rouse or Reveille (US). Calls such as The Last Post and Taps are used at the end of the day. See the links at the left to download the sheet music or audio files. More bugle calls are listed in our article about the history and cultural impact of Bugle Calls
The image below is the first page of the sheet music, and here you can download the full sheet music for Long Reveille (bugle call) in PDF format.