'Acoustic Shadow' in CW combat

[Nathan Stuart]

Have heard about the strange phenomenon of 'acoustic shadow' occurring on specific areas of battlefields during Civil War combat, whereby nearby battle sounds are unheard (or reduced in loudness). Apparently 'acoustic shadow' can occur because sound waves are absorbed, refracted or simply blown in a different direction. The sound waves may not travel because these are disrupted or blocked by physical structures (e.g. buildings), geographical features (e.g. hills) or wind currents.

Any occurrence of 'acoustic shadow' could have affected command decisions during episodes of combat.

Wonder whether there were any Civil War battles where the experience of 'acoustic shadow' might have had a material effect on the outcome of the conflict, possibly even altering its course.

 

[James R.]

In the Battle of Iuka, acoustic shadowing prevented the coordination of Grant's planned envelopment of Price's Army of the West.

 

[Sheltowee]

Five Forks, Perryville, Gaines Mill, Seven Pines, Chancellorsville, Ft Donelson, Gettysburg have all been reported as being affected by this phenomenon.

Perryville seems to get the most attention- with Buell being grossly unaware of the major fight being conducted on the federal left.

The Sounds of Silence

Acoustic shadows bedeviled commanders on both sides during the war. "I received with astonishment the intelligence of the severe fighting that

www.historynet.com

 

[major bill]

Some historians do seem to include 'acoustic shadow' in their study of some battles. I have wondered, if in some cases, this is used as an excuse.

 

[Sheltowee]

I've always thought terrain and vegetation were the primary causes. Further reading seems to indicate peculiar atmospheric causes- thermal inversions, etc.

The conditions were, on that day, just right, and likely would not have occurred on any other given day. A "perfect storm" scenario?

 

[Nathan Stuart]

Five Forks, Perryville, Gaines Mill, Seven Pines, Chancellorsville, Ft Donelson, Gettysburg have all been reported as being affected by this phenomenon.

Perryville seems to get the most attention- with Buell being grossly unaware of the major fight being conducted on the federal left.

The Sounds of Silence

Acoustic shadows bedeviled commanders on both sides during the war. "I received with astonishment the intelligence of the severe fighting that

www.historynet.com

But was the 'acoustic shadow' reported at any of these battles material? That is, did its occurrence influence a command decision made that affected the final result of the battle?

 

[Nathan Stuart]

Some historians do seem to include 'acoustic shadow' in their study of some battles. I have wondered, if in some cases, this is used as an excuse.

Think this phenomenon is real enough. Need to identify any episodes within battles where it was identified, then trace whether its occurrence affected command decisions and troop movements in a significant way.

 

[Sheltowee]

But was the 'acoustic shadow' reported at any of these battles material? That is, did its occurrence influence a command decision made that affected the final result of the battle?

At Perryville, I would contend that acoustic shadow possibly saved Bragg's army from complete destruction.
Buell had @40,000 troops unengaged, as he thought the faint firing was minor skirmishing. Had he responded aggressively, a very bad outcome for the AofT.

From Wikipedia-
The arrival of McCook's staff officer at about 4 p.m. surprised the army commander, who had heard little battle noise and found it difficult to believe that a major Confederate attack had been under way for some time. Nevertheless, Buell ordered two brigades from Schoepf's division to support I Corps. This relatively minor commitment indicated Buell's unwillingness to accept the reported dire situation at face value.

A footnote from The Grand Havoc of Battle supports that acoustic shadow has recently been noted at Perryville re-enactments. A combination of wind direction and topography.

 

[Nathan Stuart]

At Seven Pines (1862), Johnston delayed for several hours sending in much needed reinforcements (which cost him victory) to an active engagement being fought with McClellan's Army 2 miles away, because he didn't hear the sounds of the battle. Apparently an acoustic shadow occurred where a temperature inversion caused by low cloud cover led to sound wave refractions. (Richmond citizens, 10 miles away, reportedly heard the sound of the fighting that was happening during this same period).

At Chancellorsville (1863), it has been claimed that Jackson's successful flank attack on the Union Army was largely due to an acoustic shadow that shielded the sound of his attack from Hooker.

At Gettysburg (1863), on the second day, Ewell's coordinated attack with Longstreet on Meade's lines was supposed to commence when Ewell heard the sound of Longstreet's artillery barrage. However, Ewell never heard Longstreet's guns, which allowed Meade to redeploy troops along his defensive line enabling him to effectively counter the assaults. It was claimed that an acoustic shadow was created by geographical features (Cemetery Ridge and Culps Hill) that blocked the sounds as well as near-ground hot temperatures which caused sound wave refractions, and these prevented Ewell from hearing Longstreet's guns.

 

[Saphroneth]

Accoustic shadowing turns up so often in the Civil War that I have to suspect that it's sometimes used as an "excuse" rather than a true account. A quick search reveals it to go basically unmentioned as happening during the Napoleonic Wars, which really should have showcased it occurring if it was as common a thing as the commonality of ACW claims would suggest; the only exception I can find is Jena-Auerstedt where it's mentioned as a possible defence for Bernadotte.


What I suspect is that the accoustic shadow was a technical excuse for what was often simply the fog of war.

 

[Reconstructed Rebel]

I grew up just a few miles from Perryville and can attest first hand to the odd way sound travels in that area of KY.

At our house, we could plainly hear the boom of cannon on the days the soldiers at Fort Knox, 43 miles away as the crow flies, were having target practice. It was really loud. At our uncle's house which was not more than a quarter of a mile up the road, you could hear nothing but the birds singing.

It may have been used as an excuse sometimes, but acoustic shadowing is real. And it saved Bragg from having to fight the rest of the Union Army at Perryville. Blame it on the Knobs!

Knobs region - Wikipedia

en.m.wikipedia.org

 

[USS ALASKA]

Sirs, in modern day parlance with regards to electronic emitters, it is referred to as 'Terrain Masking'.

C^__^s,
USS ALASKA

 

[Nathan Stuart]

Accoustic shadowing turns up so often in the Civil War that I have to suspect that it's sometimes used as an "excuse" rather than a true account. A quick search reveals it to go basically unmentioned as happening during the Napoleonic Wars, which really should have showcased it occurring if it was as common a thing as the commonality of ACW claims would suggest; the only exception I can find is Jena-Auerstedt where it's mentioned as a possible defence for Bernadotte.


What I suspect is that the accoustic shadow was a technical excuse for what was often simply the fog of war.

Yes, I've noticed the term 'acoustic shadow' is frequently used in descriptions of combat conditions during the war.

It seems to me this term may be over-used and conveniently applied to explain inactions by commanders on the field that could more simply be attributed to the 'fog of war'.

 

[Old Soldier]

'Acoustic shadow' = "I'm deaf with all this shooting!" That is why we wear ear defenders on range.

 

[Nathan Stuart]

Acoustic shadow, fog of war (chaos), distractions, fatigue, fear etc.. There's lots of possible factors that could be attributable to participants not hearing sounds of battle.

 

[19thOhio]

If I remember correctly Union forces spread out marching to Perryville to find water. It was hot and dry. If the winds were out of the south fairly strong there could have been an "acoustic shadow" that the right wing might not hear.

 

[Nathan Stuart]

If I remember correctly Union forces spread out marching to Perryville to find water. It was hot and dry. If the winds were out of the south fairly strong there could have been an "acoustic shadow" that the right wing might not hear.

Definitely think that the intensity, velocity and direction of wind currents can be a factor impacting on the travel of sound waves.

Wind might be a factor to investigate during key episodes of battle where acoustic shadow was claimed to exist.

 

[CowCavalry]

EP Alexander discusses the phenomenon at some length in "Fighting for the Confederacy".

 

[Nathan Stuart]

EP Alexander discusses the phenomenon at some length in "Fighting for the Confederacy".

Thanks for this timely information. I'm reading his account (in early stages) presently and will particularly note Alexander's descriptions of the phenomenon.

 

[Josh The Lighthouse Guy]

Does Kenneth Noe's book about weather and climate in the war, The Howling Storm, address this issue?