A Is For Acoustic Shadow
A while back I was going through the alphabet, exploring different tidbits related to the successive letters. I got off tracks with various things, but with a shiny new blog, let’s get back in the groove. A is for acoustic shadow.
The First Battle of Manassas was fought on July 21, 1861 at Manassas Junction, Virginia, also known as Bull Run. In The Rain Crow, I have citizens pouring out of their beds and into the streets to listen to the bombardment some twenty miles away as the crow flies. Even more amazing, some commanders involved in the fighting, couldn’t hear the battle. They didn’t know which direction the battle was moving and held troops, waiting for the fighting to begin.
I use it again toward the end of Rain Crow in another situation.
The phenomenon is known as acoustic shadows. It occurred several times during the Civil War to great effect, good and bad. Another well-known occurrence was the German bombardment of Antwerp in World War I. It was heard plainly for a 30-mile radius and then 60 miles beyond the city, but not in between.
Some say acoustic shadows are where sounds go to die, but the opposite can happen also, as we have seen. Sound can “bounce” and travel greater distances or appear where it shouldn’t. One man speaks of sitting by a lake and listening to soldiers visiting around a campfire across the lake as plainly as if they were next to him. Battle sounds can seem to be coming from a different direction or many directions or no direction at all. It’s just “there.” It’s as if Mother Nature is saying, “I’d like you children to settle down and play nice for a while.”
The Battle of Fort Donnelson took place between February 11-16, 1862. This Confederate fort was in western Tennessee along the Cumberland River. Union commander Brig. Gen. Grant attempted to take the fort with the aid of Flag Officer Andrew Foote in ironclads. They met with unexpected losses and retreated five miles north where Foote conferred with Grant.
Meanwhile, back at the fort, (you have no idea how long I’ve waited to say that) Brig Gen Gideon Pillow attacked the Federals who were now being commanded by Brig. Gen. John McClernand. Grant and Foote heard nothing five miles away and had no idea a battle was going on. This was most likely because a thick blanket of snow fell the previous day in addition to a strong wind from north to south creating an acoustic shadow.
Things were looking grim when, for some unknown reason, Pillow withdrew before success and Grant showed up to save his troops. Fort Donnelson was captured unconditionally with tremendous losses to the Confederates.
The Battle of Seven Pines took place near Richmond, Virginia on May 31 and June 1, 1862. CSA Gen Joseph E. Johnson devised an elaborate three-pronged attack against Union Gen. George McClellan’s Army of the Potomac. It required perfect timing and coordination even though Johnston had little faith in his subordinates’ ability to cooperate.
Johnston’s headquarters were close to the city and he heard no sounds of battle, so he assumed they had failed to engage and didn’t send reserves until it was too late. When Johnston did visit the battlefield, he was severely wounded, paving the way for Gen. Robert E. Lee to take command.
Johnston, who was less than two miles from the battle couldn’t hear it, while citizens ten miles away heard it clearly. Some theorize the low cloud cover was responsible for the acoustic shadow.
The town of Iuka, Mississippi, population 3,000, may seem like a sleepy little southern village, but before the War Between the States, it boasted an all-female college and a male military institute. CSA Maj. Gen Sterling Price set 14,000 men in the path of Union Maj. Gen. William Rosencrans. The new commander of forces in the area, Grant, ordered Iuka attacked on two sides by Maj, Gen. E.O. C. Ord and Rosencrans.
In order to coordinate the attacks, Grant instructed Ord to wait until he heard Rosencrans attack. Due to a strong wind blowing away from Ord, he never heard Rosencrans. By the time Ord and Grant joined the battle, The Confederates spent the afternoon fighting Rosencrans, but due to the acoustic shadow, Grant and Ord never cut them off on the other side and joined in. Price had slipped the trap and escaped with all his men and marched on to join Confederate Maj. Gen. Earl Van Dorn. There they settled in for the Second Battle of Corinth against Rosencrans. Newspapers unjustly claimed Grant didn’t support because he was drunk.
Chancellorsville is perhaps best known for the unfortunate friendly fire incident that cost Gen. Stonewall Jackson his life, but it was also his last and greatest victory. Jackson led his troops on a harrowing mission to attack Maj. Gen. Joseph Hooker’s left flank. The tactic worked due to bold tactics no doubt.
Also playing in Jackson’s favor were high winds that kept Union balloons on the ground and may have refracted the sounds from Hooker.
July 1-3, 1863 saw more people killed or wounded than any other battle in the war. Gettysburg is forever seared in our consciousness, as well it should be.
On the second day, CSA Gen. Richard Ewell and CSA Gen. James Longstreet were to attack Round Top Mountain. Ewell was to begin when he heard Longstreet’s artillery barrage. Longstreet never heard it and was able to successfully defend Round Top without the additional offense.
People in Pittsburgh 150 miles away on July 1 heard the battle, but people in Taneytown only twelve miles away could not hear it.
Acoustic shadows play a part in things like road design. Sound barriers might be put up on one side of the road and not the other, or built tall when there doesn’t appear to be anyone around to be affected. Interesting how they affected battles – hadn’t realised that.
AJ, exactly. It played a huge part in the Civil War, but this phenomenon has been happening and recorded for thousands of years.
This was a fascinating read. I had never heard this concept about acoustic shadows.