The Sounds & The Fury: The Impact of Acoustics on Civil War Battles
Those sounds were to be the signal for Johnston to send in General W.H.C. Whiting to join a three-pronged assault on the Union position. At his headquarters two miles from Seven Pines, Johnson never heard the sounds, even though several of his aides swore they could hear the battle, which also was heard clearly in Richmond some 10 miles away. Denied victory and forced to do reconnaissance in a position that should have been secured, Johnston - born in Farmville at the estate from which Longwood derives its name - was wounded later that day and, in a move that altered history, replaced by Robert E. Lee.
Similar quirks of sound also hastened the end of the War when three Confederate generals, attending a shadbake behind their lines at Five Forks, couldn't hear an attack less than two miles away. Their leaderless soldiers were routed, forcing Lee to evacuate Petersburg and begin his desperate flight westward that ended eight days later at Appomattox. In between Seven Pines and Five Forks, acoustics also influenced command decisions at the battles of Gettysburg, Chancellorsville, Perryville, Iuka, and Fort Donelson.
A Longwood physics professor, Dr. Chuck Ross, has investigated these "acoustic shadows" and - in numerous journal articles, presentations to professional organizations and Civil War roundtables, and interviews with newspapers, magazines and radio stations from across the country - has become a sought-after expert on the subject and garnered national and international publicity for the College.
"These two battles were like 'acoustic shadow' bookends in Lee's career - Seven Pines launched it and Five Forks essentially ended it - with two other major battles in the middle, Chancellorsville and Gettysburg, also affected by acoustic shadows," Ross says.
Sound was important to Civil War commanders, he says, for two reasons. "They frequently send in reinforcements to where the sounds of battle were the 'hottest.' Also, when devising their battle plans, they often told subordinates to begin their assault when the sound of another engagement was heard."
Ironically, Ross's interest in Civil War acoustics began as a "side project" to his book Trial by Fire: Science, Technology and the Civil War, published in January by White Mane Publishing Company. "After I identified six or seven of these events, I tried to get to the bottom of it," he says. "I had to wade through a lot of research on weather and terrain. I'm not an acoustician, so I had a lot to learn." As a result of his well-publicized research, he has recently signed a contract, also with White Mane, for a second book, this one devoted to unusual acoustics in the Civil War. It is due to be released in January 2001.
Three factors make sound waves change directions, an effect called refraction, says Ross.
"One is temperature. Decreasing temperatures at higher altitude normally cause sound waves to bend upward. A temperature inversion, often associated with fog or widespread storms, is the unusual situation in which temperatures get warmer as you go higher. A temperature inversion can bend sound waves back toward the ground, causing a listener to hear the sound at an unusually long distance from the source. If the sound reflects off the ground, it can rise and get bent down again. If repeated, this effect can create a 'bull's-eye' pattern of rings of inaudibility far from the source.
"Another factor is called wind shear. Wind speed is greater at higher altitude, because there's less friction with the ground. The result of wind shear is that sounds headed into the wind refract or bend upward, and sounds headed downwind refract downward. Thus, sounds are always heard better at ground level when a listener is downwind from the source.
"The third factor is the absorption of sound waves by physical matter between the source of the sound and the listener. This was probably the most significant of the three factors at Seven Pines, where there was thick forest Johnston and the battle. It was also a problem at Five Forks, where a dense pine forest absorbed the sound of battle."
All three factors played a role at Seven Pines, also called Fair Oaks, fought May 31, 1862 around where Nine Mile Road meets U.S. 60 near Richmond International Airport. "Johnston suffered a triple whammy, with wind shear, temperature effects and absorption combining to place him in an acoustic shadow," says the physicist. "The weather the night before was intense. Many of the soldiers' diaries said it was the worst thunderstorm they'd ever seen, and Thaddeus Lowe (balloonist for the Union army) had trouble with observations the next day due to the wind. Some people on one side of Johnston's headquarters heard the attack, and some on the other side didn't. If it had happened as planned, Whiting's attack should have turned the tide of battle. The timing would have been good for the Confederates because the Union army was divided by the Chickahominy River. Johnston's delay allowed Union leaders to reinforce their troops on the south side of the river and the battle ended as a draw, when it should have been a Confederate victory."
In his official report Johnson wrote "Owing to some peculiar condition of the atmosphere, the sound of musketry did not reach us."
The Confederate defeat April 1, 1865, at Five Forks was critical because this intersection of five country roads between U.S. 460 and U.S. 1 protected the South Side Railroad, Lee's last supply line into Petersburg. Five Forks, 20 miles southwest of Petersburg in Dinwiddie County, marked the right flank, or end, of his paper-thin defenses around Petersburg, which had been under siege for nearly 10 months. "If a flank was captured," Ross says, "a Civil War-era army could be rolled up like a carpet." Lee had implored the commander there, General George Pickett, to hold Five Forks "at all hazards." Not expecting an imminent assault, Pickett, best known for his doomed attack at Gettysburg, and cavalry leader Fitzhugh Lee, Lee's nephew and a future Virginia governor, had gone to General Thomas Rosser's headquarters for the infamous fish fry. Lee never forgave Pickett for his momentary inattention.
"When the Federal assault came shortly afterward," according to Pursuit to Appomattox: The Last Battles in the Time-Life Books series on the Civil War, "the sound of battle did not carry the mile and a half to the site of the shadbake - perhaps owing to some 'peculiar phenomenon of acoustic shadows,' as Confederate artillery commander E. Porter Alexander later suggested. Thus the Confederates in Pickett's line had to face the onslaught with no one in overall command."