The bugle was a very important tool for communication during the Civil war. The main bugler was attached to the headquarters staff, and was always close to the commander at the front. Soldiers learned the calls of the bugle quickly, and on any given day at least four, and as many as ten, were made.
Below are just a few of the calls that soldiers would hear on a daily basis. These calls are performed by R. J. Samp.
More calls can be found here https://soundcloud.com/rjsamp/tracks