Acoustic Shadow (sometimes called Silent Battle) is kind of weird. It is a phenomenon where the sound is not heard near the cause of the sound, but the same sound is heard at a great distance from its source. With a unique combination of factors such as wind, weather, temperature, terrain topography, forest or other vegetation, and elevation, the sounds of battle are not heard at the distance that they would normally be clearly heard.

The distance at which the sound is heard can be great, even hundreds of miles, but nearby (sometimes just miles away), the sounds are not heard. The battles where the Acoustic Shadow phenomenon occurred in the Civil War are Gettysburg, Seven Pines, Iuka, Fort Donelson, Five Forks, Perryville, and Chancellorsville.

Acoustic Shadow could have a profound effect on a battle. During the Civil War, it was common for armies to be spread over great distances, and timely communication between the divided parts of an army was crucial to success on the battlefield. Army commanders must make decisions based on current knowledge of the situation before them. The sound of a battle would be a form of communication, telling a Civil War commander and his staff where a battle is taking place and what troops (including enemy troops) may be involved. If Acoustic Shadow hides the action of battle from being heard by a commander, then communication has been lost and serious consequences can result as the commander does not respond as needed to the battlefield situation.

Examples of acoustic shadow during Civil War battles:

• Battle of Gaines’s Mill – More than 91,000 men participated in the battle at Gaines’s Mill, Virginia, on June 27, 1862. Confederate commanders and troops were less than two miles from the battlefield and could clearly see the smoke and the flashes of guns and artillery. but not a sound of battle was heard for two hours. Interestingly, the sounds of the Battle of Gaines’s Mill were easily heard in Staunton, Virginia, over a hundred miles away.
• Five Forks – Fives Forks was fought from March 30 to April 1, 1865, and was part of the Appomattox Campaign. Confederate Generals George Pickett and Fitzhugh Lee were enjoying a tarpon bake with other generals north of Hatcher’s Run when the Battle of Five Forks began a short distance away. Due to Acoustic Shadow, Pickett and Fitzhugh Lee were unaware that a fight was brewing. Pickett finally responded, but was late for the battle. Pickett and Fitzhugh Lee have been criticized by Civil War historians (see Lee’s Lieutenants, III, 665-670) for failing to act on “the fearful immediacy of the crisis” (ibid., 665) at Five Forks.
• The Battle of Gettysburg: The sounds of the Battle of Gettysburg fought on July 1, 2, and 3, 1863 could be heard over a hundred miles away in Pittsburgh, but they weren’t heard just ten miles from the battlefield .