Were all the additional troops needed?

[Stryker65]

Grant's Army of the Tennessee was designed for field operations, no problem with that. Ten divisions, in three corps (XIII, XV, XVII), and attached cavalry and artillery, was enough to battle Pemberton at Champion Hill. But when it came to besieging Pemberton in Vicksburg, Grant needed an additional six divisions, in two corps (IX and XVI) to hold the lines.

If I remember correctly, IX Corps was held east of Grant's position to monitor Johnston's forces, Lauman's and Kimball's divisions garrisoned posts above and below Vicksburg, and only Sooy Smith's and Francis Herron's divisions were actually used in the siege operations.

I've never considered Grant to be a Need-Reinforcement-ASAP guy like McClellan, and I'm sure he saw some use for all those troops, but could it be, perhaps, that he did not in fact need all 30,000 reinforcements that he received? In reference to the Johnston situation, I would think that Johnston's defensive rather than offensive capabilities would be known at this point such that any forward movements by his command would be placed in doubt. If anything, he could be distracted by, say, a feint or small expedition from Richard Oglesby's corps at Corinth.

 

[Josh The Lighthouse Guy]

I've wondered this myself.

I think a big part of the reason was not simply Johnston possibly attacking, but rather the expectation there would be another assault. Pemberton surrendering only days before several undermining operations were going to be detonated saved a lot of lives on both sides.

I do think IX Corps would have been better utilized by taking Knoxville earlier, assuming XXIII Corps was also ready. But that may have only been apparent in hindsight.

 

[UCVRelics]

Grant also thought there were CS troops coming from the Mobile area. Also, all my years in the US Army we had a saying, "If in country and you need 1 tank part you ordered 3. If you were in another country you ordered 5. We would rather have it and not need it, than need it and not have it. It wasn't like the yankees were lacking in troops. There were plenty sitting around doing nothing.

 

[J. Stanley]

I did review this once and came to the conclusion that in hindsight, given how slowly Joseph Johnston moved to relieve Vicksburg, the answer is that not all the troops were needed. But without hindsight, this is not obvious.

Grant needed manpower for three things:
1) complete the siege line south of Vicksburg
2) to maintain the external line to keep Johnston out
3) continue digging towards the Vicksburg defenses for the final assault

By June 4, Johnston had amassed 31k men and 72 cannon. Grant had accurate information on Johnston's numbers, although some reports said it could be as high as 50k but emphasized that it was likely 30k. But Johnston's exact location was an issue for Grant. A lot of false alarms were raised that Johnston was bearing down on him soon.

The following is the timeline of Grant's reinforcements:

Date	Unit	Manpower
May 20	Lauman's Div. (XVI Corps)	6,322
June 4	Kimball's Div. (XVI Corps)	6,150
June 12	Sooy Smith's Div. (XVI Corps)	7,581
June 13	Herron's Div. (Army of the Frontiers)	5,190
June 17	IX Corps	8,703
Total		33,946

Lauman was deployed south of Vicksburg, but the investment of the city was still incomplete. Kimball's division was deployed to the Mechanicsburg Corridor - Kimball panicked at false reports of Johnston at the Big Black River and his division beat a panicked flight, alarming Grant. Sooy Smith's arrival beefed up the external line sufficiently that Herron's division was able to go to the southern end of the Vicksburg siege line and complete the investment.

IX Corps was supposed to be sent to the southern end to allow McClernand's XIII Corps to shorten their line and concentrate their forces for the big assault, but was instead deployed to the Mechanicsburg Corridor. It should be noted that the troops on the Mechanicsburg Corridor were still outnumbered by Johnston (albeit entrenched) and Grant was counting on Sherman to come up with 5 brigades from his and McPherson's Corps along the siege lines to restore the numerical balance.

Here is where I address the question if this was necessary. Armies don't plan on the enemy being stupid or incapable. Johnston's Army of Relief was on paper a large and capable formation and I think that in theory the Army of Relief could have overwhelmed a portion of Grant's army and freed Pemberton had it attacked in early June. The window of opportunity closed in mid-June when Grant's reinforcements arrived. This is of course ignoring Johnston's inclinations and very real logistical difficulties of the Army of Relief - the Army of Relief didn't have a sufficient wagon train to sustain a campaign away from the railroads for more than 4 days, had shockingly poor understanding of the path to Vicksburg and it didn't have a pontoon bridge for the Big Black until late June (though water levels did fall in mid June).

Until the arrival of Sooy Smith's division, the external line was pretty thin though ably helped by the hilly, broken terrain and entrenchments. With Sooy Smith's division, the line was manned by 15k men, with the promise of 10k reinforcements under Sherman. I think it could be argued that IX Corps was excessive, certainly some IX Corps troops had this impression after they landed. And the diversion of the IX Corps did have the negative impact of causing Rosecrans to delay the Tullahoma Campaign, which could have been more effective with less rainy weather in early-mid June. But these reinforcements were ordered well in advance, with units arriving 1-2 weeks after receiving instructions. I should also note that the troops of the XVI Corps were from Grant's own department and mostly doing garrison duty and the deployment of Herron's division was not really to the detriment of Federal forces in the Trans-Mississippi. Only the IX Corps has a clear opportunity cost for the Federals.

 

[Stryker65]

Here is where I address the question if this was necessary. Armies don't plan on the enemy being stupid or incapable. Johnston's Army of Relief was on paper a large and capable formation and I think that in theory the Army of Relief could have overwhelmed a portion of Grant's army and freed Pemberton had it attacked in early June. The window of opportunity closed in mid-June when Grant's reinforcements arrived. This is of course ignoring Johnston's inclinations and very real logistical difficulties of the Army of Relief - the Army of Relief didn't have a sufficient wagon train to sustain a campaign away from the railroads for more than 4 days, had shockingly poor understanding of the path to Vicksburg and it didn't have a pontoon bridge for the Big Black until late June (though water levels did fall in mid June).

Until the arrival of Sooy Smith's division, the external line was pretty thin though ably helped by the hilly, broken terrain and entrenchments. With Sooy Smith's division, the line was manned by 15k men, with the promise of 10k reinforcements under Sherman. I think it could be argued that IX Corps was excessive, certainly some IX Corps troops had this impression after they landed. And the diversion of the IX Corps did have the negative impact of causing Rosecrans to delay the Tullahoma Campaign, which could have been more effective with less rainy weather in early-mid June. But these reinforcements were ordered well in advance, with units arriving 1-2 weeks after receiving instructions. I should also note that the troops of the XVI Corps were from Grant's own department and mostly doing garrison duty and the deployment of Herron's division was not really to the detriment of Federal forces in the Trans-Mississippi. Only the IX Corps has a clear opportunity cost for the Federals.

I think that was the main problem with the Army of Relief -- it is abundantly clear that the Confederacy had the manpower to scrape up five divisions and amass the strength to counterattack, but it doesn't seem that they brought enough transportation, which makes sense since most of the Army's units were individual brigades from all over the Confederacy -- I would assume that only Breckinridge's division, being pre-existing, had their own transportation.

Just wondering, why did Rosecrans need IX Corps? Since they were in Kentucky and East Tennessee, wouldn't XXIII Corps have been able to garrison those points?

 

[J. Stanley]

Just wondering, why did Rosecrans need IX Corps? Since they were in Kentucky and East Tennessee, wouldn't XXIII Corps have been able to garrison those points?

According to Dave Powell and Eric Wittenberg's book on Tullahoma, Rosecrans was expecting Burnside to coordinate with him through an invasion of East Tennessee to coincide with Rosecrans' own offensive. The XXIII Corps was earmarked for the thrust into East Tennessee, but the IX Corps' departure derailed the plans and XXIII Corps was dispersed to garrison Kentucky.

In hindsight, Rosecrans really didn't need Burnside to act at all - though it would have been nice to pin down and defeat the Confederate defenders in East Tennessee. I think it's fair to critique Rosecrans for his incorrect interpretation of the movements around Bragg's army and say that Rosecrans caused his own Tullahoma offensive to fall short of its promise by delaying it.

On a side note, if the IX Corps had been left in Kentucky, John Hunt Morgan might have had a tougher time getting through Kentucky to the North.

 

[tony_gunter]

Grant's Army of the Tennessee was designed for field operations, no problem with that. Ten divisions, in three corps (XIII, XV, XVII), and attached cavalry and artillery, was enough to battle Pemberton at Champion Hill. But when it came to besieging Pemberton in Vicksburg, Grant needed an additional six divisions, in two corps (IX and XVI) to hold the lines.

If I remember correctly, IX Corps was held east of Grant's position to monitor Johnston's forces, Lauman's and Kimball's divisions garrisoned posts above and below Vicksburg, and only Sooy Smith's and Francis Herron's divisions were actually used in the siege operations.

I've never considered Grant to be a Need-Reinforcement-ASAP guy like McClellan, and I'm sure he saw some use for all those troops, but could it be, perhaps, that he did not in fact need all 30,000 reinforcements that he received? In reference to the Johnston situation, I would think that Johnston's defensive rather than offensive capabilities would be known at this point such that any forward movements by his command would be placed in doubt. If anything, he could be distracted by, say, a feint or small expedition from Richard Oglesby's corps at Corinth.

You're forgetting that Grant had a massive cavalry advantage moving to invest Vicksburg, but was greatly outnumbered once Jackson's Division arrived.

Johnston could move behind his cavalry and Grant wouldn't know exactly where the blow would land.

 

[tony_gunter]

I did review this once and came to the conclusion that in hindsight, given how slowly Joseph Johnston moved to relieve Vicksburg, the answer is that not all the troops were needed. But without hindsight, this is not obvious.

Grant needed manpower for three things:
1) complete the siege line south of Vicksburg
2) to maintain the external line to keep Johnston out
3) continue digging towards the Vicksburg defenses for the final assault

By June 4, Johnston had amassed 31k men and 72 cannon. Grant had accurate information on Johnston's numbers, although some reports said it could be as high as 50k but emphasized that it was likely 30k. But Johnston's exact location was an issue for Grant. A lot of false alarms were raised that Johnston was bearing down on him soon.

The following is the timeline of Grant's reinforcements:

Date	Unit	Manpower
May 20	Lauman's Div. (XVI Corps)	6,322
June 4	Kimball's Div. (XVI Corps)	6,150
June 12	Sooy Smith's Div. (XVI Corps)	7,581
June 13	Herron's Div. (Army of the Frontiers)	5,190
June 17	IX Corps	8,703
Total		33,946

Lauman was deployed south of Vicksburg, but the investment of the city was still incomplete. Kimball's division was deployed to the Mechanicsburg Corridor - Kimball panicked at false reports of Johnston at the Big Black River and his division beat a panicked flight, alarming Grant.

It's been a while since I've read about Kimball's foray, but I got the impression Kimball was unsure what troops Johnston had deployed into the Mechanicsburg Corridor and was shocked to discover that he was within striking distance of an entire Confederate division when he began beating a hasty retreat in the brutal June heat.

I do remember every regiment reporting several wagons loaded with victims of heatstroke.

 

[J. Stanley]

It's been a while since I've read about Kimball's foray, but I got the impression Kimball was unsure what troops Johnston had deployed into the Mechanicsburg Corridor and was shocked to discover that he was within striking distance of an entire Confederate division when he began beating a hasty retreat in the brutal June heat.

I do remember every regiment reporting several wagons loaded with victims of heatstroke.

Based on my understanding from Timothy B. Smith and Michael Ballard's respective books, Kimball was badly scared by false information about the strength of Confederate forces to his front. IIRC, he thought there were 20k Confederates inside the Mechanicsburg Corridor. The only division anywhere close to him was W.H.T. Walker's division at Yazoo City, about 8k man strong. So Kimball was right that there is an enemy force within striking range - they were 20 miles or so apart- and Kimball was outnumbered by about 2k men or so. But Kimball badly exaggerated the danger he was in, though to be fair, they didn't have enough cavalry to properly scout as you mentioned above.

 

[Stryker65]

Kimball didn't even have any artillery, either -- the two batteries attached to his division had been left at Jackson (Tennessee).

 

[tony_gunter]

Based on my understanding from Timothy B. Smith and Michael Ballard's respective books, Kimball was badly scared by false information about the strength of Confederate forces to his front. IIRC, he thought there were 20k Confederates inside the Mechanicsburg Corridor. The only division anywhere close to him was W.H.T. Walker's division at Yazoo City, about 8k man strong. So Kimball was right that there is an enemy force within striking range - they were 20 miles or so apart- and Kimball was outnumbered by about 2k men or so. But Kimball badly exaggerated the danger he was in, though to be fair, they didn't have enough cavalry to properly scout as you mentioned above.

Yeah, Johnston dispersed his army to feed them. Walker to Yazoo City, Loring to Canton, Breckinridge to Jackson. Not sure where French was?

Still, outnumbered, within striking distance of the enemy, and 25 miles deep into enemy territory is a dangerous position.

 

[tony_gunter]

Kimball didn't even have any artillery, either -- the two batteries attached to his division had been left at Jackson (Tennessee).

He had at least one battery, Battery B 1st Illinois light artillery.

Edit: detached from Blair for this mission.

 

[Irishtom29]

Grant didn't want another Turin.

 

[tony_gunter]

Kimball didn't even have any artillery, either -- the two batteries attached to his division had been left at Jackson (Tennessee).

Here's a diary from 1st Illinois Battery B during the expedition. They reported a very different experience than the infantry, who all struggled with heat exhaustion during the march.

Question: did all artillery troops have horses, and that's why they fared so well, or were these guys just better acclimated to the heat?

https://www.jstor.org/stable/40190639?read-now=1&seq=3#page_scan_tab_contents

 

[Stryker65]

Here's a diary from 1st Illinois Battery B during the expedition. They reported a very different experience than the infantry, who all struggled with heat exhaustion during the march.

Question: did all artillery troops have horses, and that's why they fared so well, or were these guys just better acclimated to the heat?

https://www.jstor.org/stable/40190639?read-now=1&seq=3#page_scan_tab_contents

Kimball's division were all recently-arrived Illinois, Michigan, and Wisconsin regiments, who had not fought in any major field actions until now, garrisoning Jackson and other points until May. The only regiment with any field experience in the division was the 3rd Minnesota, which had been captured at First Murfreesboro and then fought in the Dakota Wars. It may have been that difference in experience that led to Battery B (an experieced, long-serving unit) being better acclimated.

 

[tony_gunter]

Kimball's division were all recently-arrived Illinois, Michigan, and Wisconsin regiments, who had not fought in any major field actions until now, garrisoning Jackson and other points until May. The only regiment with any field experience in the division was the 3rd Minnesota, which had been captured at First Murfreesboro and then fought in the Dakota Wars. It may have been that difference in experience that led to Battery B (an experieced, long-serving unit) being better acclimated.

Man, reading that diary makes it sound like it was a regular vacation hike. Picking berries, raiding cupboards, catching lambs for dinner, bathing in clear springs.

The infantry were like WHAT FRESH HELL IS THIS PLACE