Tuesday, August 7, 2007

The Gap - part 6

If Wood remains in position what happens?

At some point Longstreet's weight of numbers would have likely pushed Wood's force back to the Dyer defensive line. With this visible threat to his right flank Rosecrans would have kept some men in that vicinity. It is logical to believe that once the size of Longstreet's attack had been known Rosecrans would have suspended the movement orders for Major General Philip Sheridan and Brigadier General Horatio Van Cleve's divisions and retained them in that area. This would have left Rosecrans with Crittenden's artillery, Colonel John T. Wilder's brigade and Brigadier General Jefferson C. Davis, Wood, Sheridan, and Van Cleve's divisions to defend his right flank in the Dyer Ridge area. Major General Gordon Granger had Brigadier General James Steedman's two brigade division of the Reserve Corps in motion at about 1:30 PM and arrived at Snodgrass Ridge around 2:30 or 3 PM. If he had been needed at Dyer Ridge he could have been brought there soon after his arrival at Snodgrass Ridge, certainly by 3:30 P.M.

Dyer Ridge, overlooking the flat ground to the east, offers open fields of fire and a fair amount of elevation change. The distances from the Glenn-Kelly Road (which is the approximate tree line) to the defensive positions along Dyer Ridge range from 300 yards at the southern flank at Lytle Hill to 500 yards where the Union artillery was placed overlooking Dyer Field. The northern extremity of Dyer Field (where the South Carolina monument is now) is a little over 300 yards from the road. The Dyer House is also about that far from the road, while Rosecrans' headquarters is over 600 yards from the road. The elevation differences from the road to the defensive line are pretty steady at about 70 feet higher. The northern extremity of Dyer Ridge is 75 feet higher than the road, at the artillery line it is 70 feet and at Lytle Hill it is 60 feet. The Dyer house is about the same elevation as the road and Rosecrans' headquarters is about 35 feet higher. While not significant distances or heights they would offer some help to the defenders.

According to Hardee’s Rifle and Light Infantry Tactics, the standard training manual for Civil War soldiers, the common march time was 90 steps a minute with a 28 inch stride and double quick as 165 steps a minute with a 33 inch stride. That means to cover the 300-500 yards from the road to the top of the ridge the attackers would have been under fire for 2-3 minutes of quick time or 4-7 minutes at common march. Assuming that an artillery piece could fire about 2 rounds a minute the attacking Confederates would have been subjected to approximately 4-14 rounds of canister from each gun. The supporting Union infantry would also have fired roughly the same number of volleys, perhaps a few more. The parts of the ridge that were closer to 500 yards away from the tree line would be able to fire a significant amount of canister and musketry. Other portions of the defenses would not be able to fire as much; but if Wood had previously battered Longstreet’s column, this fire might have been enough to stop that attack. Future Confederate attacks would also probably have very little artillery support as the nearby tree line would prevent them from moving much up close. It is possible that the Confederates could have put artillery in Brotherton Field and fired from that position against Dyer Ridge but, at least initially, there would have been a tree line that would have interfered with that fire.

1 comment:

Dave Powell said...

Nick,

Some comments:

First, some refinements of the deployments.

1. Van Cleve. Nominally this command had three brigades, but Barnes was already loaned to Wood. By the time Longstreet's attack begins, a second Brigade - Dick's - is already in Kelly Field, and not available to help in Dyer Field. This left only Sam Beatty's Brigade, currently supporting Brannan, available to help Wood.

2. Steedman's arrival actually comes sooner than you show. His two brigades report to Thomas by about 2 pm, at the same time Van Derveer's men are retrieved from the Kelly farm 'bull pen' at the South end of Kelly Field.

3. It is a misnomer to call Davis's command a 'division' at this point. It is true that Davis still has two brigades (Martin and Carlin) but they were in bad condition after the fighting on the 19th, and the whole division numbered no more than 1200 men - an average sized brigade. Carlin was on the line, Martin in support.

4. Sheridan and wilder seem about right.

Thus, the to build this proposed line, the Federals can call on Wood - (with the addition of Barmes about 4400 men) Sam Beatty of Van Cleve - 1300 men, Sheridan - about 4000 men after sept 19 casualties, Wilder- maybe 2000 men, and Davis - no more than 1200 men. Ten brigades, and roughly 13,000 men. Not a bad force with which to repulse a frontal attack.

In fact, those portions of Longstreet's attack that face a Union line instead of a hole are initially repulsed. McNair is stopped by Brannan, and Deas' brigade falters in front of Carlin. This bodes reasonably well for your counter-factual.

But...


The problem is that Davis' line is hopelessly compromised. His 1200 men face 4700 men in Hindman's Division. Manigault's entire brigade outflanks Davis to the south. Even if Wood never moves a man, Davis' line is fatally compromised.

I think it impossible for Davis to form an effective defense against Hindman. Manigault and Anderson can and will manuver against his flank, and rout it before any help can arrive. In every circumstance at Chickamauga, a unit whose flank was turned or exposed in this manner could not stand. There are more than 15 instances on the field where this happened.

If Davis goes, then, you have the same problem that rolled up Brannan's line earlier - regiment after regiment gets chewed up trying to re-orient against a flank attack while at the same time dealing with a renewed frontal attack from Longstreet's second line. Connell and Croxton's brigade fights between 11 am and noon in Poe field demonstrate what will happen.

Thus, it is a fair bet that Davis is shattered, and at least half of Wood is swept away before there is any chance of successfully falling back into Dyer Field.

Thus, instead of Ten brigades, now we have no more than about 6 (Sheridan, part of Wood, and S Beatty) trying to form a line on Dyer ridge. Assuming Wilder receives the attack at Widow Glenn's normally, and rebuff's Manigault, you still have a huge line to cover (from Lytle Hill to North Dyer Field and Harker's Knoll) with very few troops.

Historically, Sheridan's division and Mendenhall's gun line caught enough of the Rebel's attention that a new line could form on Horseshoe Ridge. While the fight in Dyer field might be bloodier and more difficult for the Rebels in your scenario, I doubt it will materially change the overall evolution of the battle. Brannan might be withdrawn more compactly, and more coherently, and Steedman might come up less spectacularly, but I still think the battle will end up on Horseshoe - just with an improved Union chance of holding it. At the very least, Thomas will have more ammo up there, because Brannan and Wood's trains will likely not be swept off the field with McCook.

But a stabilized line in Dyer Field? Frankly I don't see it happening.

This is one of the counter-factuals I gamed when I was designing my regimental level wargame on the battle. Wood is still usually in too much trouble to withdraw effectively after Davis collapses, and there is just no way I can see that Davis doesn't collapse.

Dave Powell