Cavalry On The Flanks

I am a novice in CW tactics, but am more familar with Roman tactics. For the Romans, cavlary was posted on the flanks:

1) Counter an attack on the flank by the opponent's cavalry. (Spearmen could also perform this duty).

2) Used to exploit an break in the opponent's line; charging from the flank or rear into a wavering unit.

Well...will wait for experts to respond and see how I did. 😉
 
How often was cavalry actually used to guard or attack flanks during ACW battles?

Bull Run 1861: cavalry played little role aside from some harassment of the Union rout (more in imagination than reality)

Wilson's Creek: little cavalry present?

Peninsular Campaign & Seven Days: other than Stuart's ride and a failed counterattack at Gaines Mill cavalry was little used

Shiloh: negligible cavalry on either side. Terrain wasn't conductive to cavalry anyway.

Bull Run 1862: Fitz Lee guarded Jackson's left flank. If Pope had used his cavalry to guard his left he wouldn't have been routed.

Antietam: flanks were mostly anchored on the Potomac so cavalry wasn't relevant.

Fredericksburg: Confederate harassment of the Union left.

Perryville: negligible cavalry

Stones River: Cavalry of both sides on the flank farthest from the namesake river. Bragg might have accomplished much with more cavalry on his left hook, but I think much of it was off raiding?

Chancellorsville: Union cavalry mostly raiding, without enough on the open flank. Terrain was unfavorable to cavalry.

Gettysburg: Union cavalry protecting both flanks during parts of the battle.

Chickamauga: Union cavalry and mounted infantry delaying actions, but I don't think much flank activity. Union left could have used some cavalry as Thomas was in danger at one point on the final day. Confederate cavalry was off in its own world.

Chattanooga: cavalry not directly involved in the battle.

Overland Campaign: cavalry mostly between the armies (when not off raiding), not on the flanks.

Atlanta Campaign: cavalry not very relevant; mostly failed Union raids

Petersburg: Union failure to screen their left resulted in the Beefsteak Raid.

Shenandoah 1864: Union cavalry used to turn Confederate flanks.

March to the Sea: Kilpatrick riding on Sherman's flanks, distracting Wheeler.
 
My understanding is that one of the major goals of cavalry was to provide screening of an army's moving infantry columns to protect that force and to prevent an enemy from gaining intelligence on the size, nature, and movement of the opposition. Raiding in the rear of an enemy may have been more glamorous, as was the preference of cavalrymen such as Stuart, Wheeler, and Sheridan, but their real purpose should have been the direct protection of the main army.
 
Raiding in the rear of an enemy may have been more glamorous, as was the preference of cavalrymen such as Stuart, Wheeler, and Sheridan, but their real purpose should have been the direct protection of the main army.

In fairness to Stuart, 2 of his 3 big raids were successful (albeit during a time when the AOTP cavalry was poorly organized and use): disruptive, bad for Union morale, brought back useful intelligence, and did not interfere with Lee's operations (because both times the ANV was stationary and on the defensive).
 
How often was cavalry actually used to guard or attack flanks during ACW battles?

Bull Run 1861: cavalry played little role aside from some harassment of the Union rout (more in imagination than reality)

Wilson's Creek: little cavalry present?

Peninsular Campaign & Seven Days: other than Stuart's ride and a failed counterattack at Gaines Mill cavalry was little used

Shiloh: negligible cavalry on either side. Terrain wasn't conductive to cavalry anyway.

Bull Run 1862: Fitz Lee guarded Jackson's left flank. If Pope had used his cavalry to guard his left he wouldn't have been routed.

Antietam: flanks were mostly anchored on the Potomac so cavalry wasn't relevant.

Fredericksburg: Confederate harassment of the Union left.

Perryville: negligible cavalry

Stones River: Cavalry of both sides on the flank farthest from the namesake river. Bragg might have accomplished much with more cavalry on his left hook, but I think much of it was off raiding?

Chancellorsville: Union cavalry mostly raiding, without enough on the open flank. Terrain was unfavorable to cavalry.

Gettysburg: Union cavalry protecting both flanks during parts of the battle.

Chickamauga: Union cavalry and mounted infantry delaying actions, but I don't think much flank activity. Union left could have used some cavalry as Thomas was in danger at one point on the final day. Confederate cavalry was off in its own world.

Chattanooga: cavalry not directly involved in the battle.

Overland Campaign: cavalry mostly between the armies (when not off raiding), not on the flanks.

Atlanta Campaign: cavalry not very relevant; mostly failed Union raids

Petersburg: Union failure to screen their left resulted in the Beefsteak Raid.

Shenandoah 1864: Union cavalry used to turn Confederate flanks.

March to the Sea: Kilpatrick riding on Sherman's flanks, distracting Wheeler.
Raymond, MS: McPherson stripped his command escort companies to form cavalry screens on his flanks. This screen detected the flanking movement of the 10th/30th/50th TN infantry, and a reserve brigade was sent out to check them.
 
In fairness to Stuart, 2 of his 3 big raids were successful (albeit during a time when the AOTP cavalry was poorly organized and use): disruptive, bad for Union morale, brought back useful intelligence, and did not interfere with Lee's operations (because both times the ANV was stationary and on the defensive).
Yes, there were obviously good examples of raids that obtained important intel as did Stuart when locating the enemy's flanks, but those may more properly be considered as part of the cavalry's valid screening function. Wheeler often performed similar functions when safeguarding the AoT in Kentucky and Tennessee, although some of his forays or raids whose purpose went beyond simply protection were not as successful.
 
Raymond, MS: McPherson stripped his command escort companies to form cavalry screens on his flanks.
By comparison, General George McClellan kept his calvary together as reserves at Antietam and later in afternoon, he moved them to Right flank to guard against any enemy r movement. In doing this, he blinded his corps from locating river crossings and was surprised by late arrival of Hill’s division on his Southern flank.
 
By comparison, General George McClellan kept his calvary together as reserves at Antietam and later in afternoon, he moved them to Right flank to guard against any enemy r movement. In doing this, he blinded his corps from locating river crossings and was surprised by late arrival of Hill’s division on his Southern flank.

Antietam does not seem like a battle where cavalry could have been effectively employed by either side due the terrain on the flanks.

How was McClellan's cavalry supposed to learn of Hill's arrival? The entire Burnside/Cox corps had to cross a single bridge then move uphill toward Sharpsburg. I doubt getting cavalry across as well and past a whole corps was practical.

Stuart was effectively sidelined during the battle too, screening the artillery on Nicodemus Hill.
 
How was McClellan's cavalry supposed to learn of Hill's arrival? The entire Burnside/Cox corps had to cross a single bridge then move uphill toward Sharpsburg.
They would likely know the route Hill had to travel. And McClellan kept his cavalry corralled on the North flank.

According to Sears, Rodman and Scammon had no guides and didnt know how far it was to Snavely’s Ford. When they found it they didnt expect to find steep banks.
There were one or two other fords that were not located by the infantry until the afternoon.

Late in the day, Longstreet tried to gather units and stragglers to sweep around the North flank. I think he knew there were no Union cavalry there—instead he found a long line of artillery. It just seems the Confederates was not concerned about Union cavalry.

I hope to learn more of the terrain when I attend the Muster next month
 
At Antietam, the main body of cavalry was kept in the centre, and was advanced over the Portertown bridge. They had instructions to charge if there was an opportunity, and McClellan did ask Pleasonton whether he could charge the flank of the Sunken Road position. This body was:
  • Averell's Brigade, under Col. Childs (then Rush, vice Childs KIA)
    • 5th United States (Capt. Whiting)
    • 4th Pennsylvania (Lt Col Kerr, vice Col Childs, brigadier)
    • 6th Pennsylvania (9 coys) (Col Rush, then Lt Col Smith vice Rush, to brigadier)
  • Pleasanton's Own Brigade, under Col. Farnsworth
    • 8th Illinois (Maj Medill, vice Col Farnsworth, brigadier)
    • 3rd Indiana (Maj Chapman)
    • 1st Massachusetts (Col Williams)
  • Horse Artillery
    • Battery A, 2nd US Artillery (Capt Tidball, 6 Ordnance Rifles)
    • Battery B&L, 2nd US Artillery (Capt Robinson, 4 Ordnance Rifles)
    • Battery M(-), 2nd US Artillery (Lt Hains, 4 Ordnance Rifles)
    • Battery C&G(-), 3rd US Artillery (Capt Gibson, 4 Ordnance Rifles)
The two corps on the flanks had a regiment each attached to them to cover the flanks of the army and scout:
  • 3rd Pennsylvania Cavalry - attached to 1st Corps on the right flank
  • 6th New York Cavalry (2 Bns only) and a battalion of the 1st Maine Cavalry - attached to 9th Corps on the left flank
The only other formed large bodies were the 3rd battalion of the 12th Pennsylvania Cavalry and a battalion of the 2nd US Cavalry (with the McClellan Dragoons attached). They were on provost duties.

Burnside had, in addition to his escort of 4 companies, the equivalent of a full strength cavalry regiment for a total of 16 cavalry companies/ 8 squadrons. He was not short of cavalry. The signals station observed AP Hill crossing the Potomac and gave Burnside (edit) 90 minutes warning of his approach.

The main body did not go to the right. However, Col. Davis of the 8th New York Cavalry (Harper's Ferry escapees) didn't need to wait for the order from McClellan (which was sent), but rode "to the sound of the guns". Arriving near McClellan's right flank, he reported to Hooker's HQ. Buford (the Chief-of-Cavalry) was there, and had them fall in with the 3rd Pennsylvania Cavalry as an ad-hoc brigade. They skirmished with Stuart's attempted breakout there on the afternoon of the 17th.
 
Why is having cavalry on the flanks preferable to having infantry? Is it because you're more mobile and can redeploy your men to faster to avoid getting hit from the rear?
Cavalry could not be used in the principal line of battle for a couple of reasons... namely (from Gen. Hallecks' textbook for volunteer officers)
1631210516431.png


However, Halleck notes the European's experience showed that cavalry could overthrow infantry already engaged with other infantry, and disordered as a result... by striking at their flanks...

1631210737220.png


A typical formation of an army for battle...

1631210832790.png

1631210911101.png


And at best, the cavalry in battle...

1631210971945.png



All that said, there were few incidents of stunning cavalry charges sweeping the enemy as occasionally happened in the Napoleonic wars. the Civil War cavalry commanders admitting that their commands did not do such, because in part they were not armed or trained for it specifically, but principally as light dragoons or as "mounted riflemen" (or cavalry) when occasion required. According to General T.L. Rosser of the CSA:

1631211584878.png

1631211609817.png
 
By comparison, General George McClellan kept his calvary together as reserves at Antietam and later in afternoon, he moved them to Right flank to guard against any enemy r movement. In doing this, he blinded his corps from locating river crossings and was surprised by late arrival of Hill’s division on his Southern flank.
The actually critical river crossing (the one Hill used) was well in the Confederate rear. Here's a map showing the positions at the end of the day:

LLoR.jpg



The line of retreat is the same one that Hill used to approach the battlefield. As you can see, for the cavalry to be able to detect Hill's approach it would have to be well behind the main Confederate line of resistance.


As it happens, cavalry on the left flank would have been largely redundant - a signals station saw Hill's approach well ahead of time*, and this warning was transmitted to Burnside. Burnside however either ignored the warning or failed to pass it on to his tactical commander (Cox), or if it was passed on Cox failed to react to it.


The problem at Antietam was not a lack of cavalry on the flank.


* 2PM: "Yes; they are moving now a strong force of infantry from Shepherdstown into the woods west of Sharpsburg and northerly to our right." (emphasis mine, Shepherdstown was the crossing)
Hill didn't hit 9th Corps until 3:30 to 3:40 PM, so there was ~90 minutes of lead time.
 
The actually critical river crossing (the one Hill used) was well in the Confederate rear. Here's a map showing the positions at the end of the day:

View attachment 413533


The line of retreat is the same one that Hill used to approach the battlefield. As you can see, for the cavalry to be able to detect Hill's approach it would have to be well behind the main Confederate line of resistance.


As it happens, cavalry on the right flank would have been largely redundant - a signals station saw Hill's approach well ahead of time, and this warning was transmitted to Burnside. Burnside however either ignored the warning or failed to pass it on to his tactical commander (Cox), or if it was passed on Cox failed to react to it.


The problem at Antietam was not a lack of cavalry on the right flank.
If I am remembering correctly, the Confederates had Col. T.L. Munford's brigade of cavalry (small as it was) posted on their extreme right to cover the fords over the river during the battle.
 
If I am remembering correctly, the Confederates had Col. T.L. Munford's brigade of cavalry (small as it was) posted on their extreme right to cover the fords over the river during the battle.
The Laurel Brigade which Munford commanded at Antietam was nearly 2,000 strong (in effectives) at the end of the Northern Virginia campaign, so it might not have been as small as all that. Stuart had 5,761 cav PFD (in CS definitions) at the end of the campaign and pretty much exactly the same at the start, so very few casualties - it's quite possible Munford had upwards of 1,500 effectives on the field.
 
As it happens, cavalry on the left flank would have been largely redundant - a signals station saw Hill's approach well ahead of time*, and this warning was transmitted to Burnside.
Right but it was a little late.
Snavely’s Ford was further South and around the bend. See Purple added to Map and Rodman in Blue.

Why didnt any cavalry patrols probe closer to the Potomac— as marked in Yellow? Not a flanking attack but get some eyes on Lee’s forces and only route of retreat.

265577B2-0FC5-4A8E-AFE9-9F96A1DA012D.jpeg
 
The Laurel Brigade which Munford commanded at Antietam was nearly 2,000 strong (in effectives) at the end of the Northern Virginia campaign, so it might not have been as small as all that. Stuart had 5,761 cav PFD (in CS definitions) at the end of the campaign and pretty much exactly the same at the start, so very few casualties - it's quite possible Munford had upwards of 1,500 effectives on the field.

Munford had the 2nd, 7th, and 12th VA Cav. regiments (From memory; the rest of the brigade being detached as I recall), and these were very slight outfits so far as what they could muster in the field. At Poolesville several days before Antietam the 12th had about 80 riders (Dennis Fry), maybe a couple dozen of whom were killed, wounded, or captured there and near Sugar Loaf mountain.

Mr. Hoptak's book on the Battle of South Mountain says a few days later in the fight at Crampton's Gap, Munford's brigade; the 2nd VAC had 120 or so men, so this was an even smaller brigade by Antietam. No doubt after the campaign the units rendezvoused, and with so few men across the Potomac casualties would have to have been slight.

Numbers aside, regarding Antietam, is it known WHERE Munford's line was posted? Near the mouth of the creek?
 
Right but it was a little late.
Snavely’s Ford was further South and around the bend. See Purple added to Map and Rodman in Blue.

As for what you mean about "a little late", when do you think the alarm should have been raised? The signals station saw Hill's movement when it happened, at the speed of light, because that's how observation works.

As for Snavely's Ford, I'm not sure what you're suggesting - the issue was getting over the Rohrbach Bridge, and it's an issue because Burnside screwed up his entire deployment. He had some organic cavalry as it happens (3 companies in the Kanawha Division and another 9 at corps level) but it shouldn't have taken him a flanking move over Snavely's Ford to take the Rohrbach Bridge and it didn't take him a flanking move - it took one of his division commanders conducting a proper attack with artillery support, the sort he should have prepared hours before. This drove off the defenders of the bridge and allowed it to be captured.


Why didnt any cavalry patrols probe closer to the Potomac— as marked in Yellow? Not a flanking attack but get some eyes on Lee’s forces and only route of retreat.
Probably because there's only so much cavalry to go around, and because, as Munford's cavalry was out there, there wasn't enough available to overmatch Munford, and because there was that line-of-sight observation of the area rendering it to some extent redundant.

The question here is what strength this cavalry patrol would have to have been in, and what the benefit from it would have been, and what the cost to other activities would have been. We can take it as read that the cavalry patrol would have to have been in sufficient strength to overcome Munford's 41 companies of cavalry, which is enough that it's not far off being the Union's main cavalry effort, and what's the benefit?
 
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