Friday, September 25, 2015

19th Century What Ifs: US vs. France and Mexico 1866 Part II: Operational Plans

19th Century What if :The Franco-American War 1866-1868
Aka “The Second Mexican War”, “La Guerre per la Follie Napoleon”
Part II

In the previous post I laid out a potential story of how a war between France and the US could come about in the 1864-1866 period. I also postulated some potential forces.  I will now lay out the potential operational plans of Marshall Bazaine and General Sheridan, the commanders on the ground.

First let me explain why I think the forces I postulated in the previous post are probably the upper limit of what the US and France will have available early in the war.

For the US.

First. The end of the civil war in 1866 will probably see the massive exit of volunteers and the end of conscription. My guess is that even troops whose volunteer term is not up will clamor to go to home (I can see them saying "we signed up to fight the sessechs, not some damn frenchie in Texas land").  There will likely thus be a large decrease in US manpower. Historically one of the two corps of Sheridan's "Army of Occupation" that faced off with Napoleon III at the Rio Grande was made up exclusively of long term service USCT (United States Colored Troops). My expectation is that initially the forces at Sheridan's disposal will be made up of the 19 US Regular Infantry regiments, 6 Cavalry Regiments, and 5 Artillery Regiments, plus a number of USCT (considering that there were 135 Regiments of USCT, there are enough to create a good force).

Second. large parts of the US army will have to be used for police and occupation duties. Remember this is a longer war then historically, and probably more bloody as Lee and Johnston were able to combine in the Carolinas. Bitterness may be higher than in history, devastation worse.

Third. Naval issues. In this scenario remember that France has already a important naval presence in the Gulf Region (with a fortified base in Vera Cruz, and probably Martinique or Guadelupe). Now I have seen lots of debates over the quality and size of the French and US navies in this period. I decided to use political science to give me a more general picture. Brian Crisher and Mark Souva collected naval data for the post 1864 period (you can find a draft of their published paper here
Power at Sea, and the data here Power at Sea Dataset).

There data shows the following comaprisons between the US and French navies in total tonnage

1866 France/US= 170694/ 140070 
1867 France/US=192440/141779
1868 France/US =217051/148982

As we can see the distribution of material capabilities is such that we cannot assume a freedom of the US navy to ferry troops via the sea from the Eastern Theater to Texas.  This means that forces will have to entrain and then get off at Vicksburg and march to the area of operations. This is a very large area to cover on foot, so my belief is that it will take a long period for any reinforcements to come from the East to Texas. Thus at least for the first year of the war, Bazaine and Sheridan have their own private hell, and must fight with what is available. Remember that the rail-network is not very developed in this part of the US.

Fourth. The war will without doubt create some volunteer waves, especially in the Western states and some of the old Confederacy. But my feel is that the large numbers of USCT that will have to be used, and the greater bitterness of this longer war, will damp the number of ex-Confeds who wear blue to fight the French and Mexicans. Instead I see a mix of green and veteran volunteers (mostly green) complementing the Regulars and USCT Sheridan has available.

For France

I have already noted the naval situation above, and just as it puts limits on the ability of the US to bring troops to the theater of the war, so it does for the French. To this add the political limitations that Napoleon III faces at home. He has to keep this war cheap for France, both in lives and money, and must sacrifice political power in France for freedom of action in Mexico. This means that his ability to raise troops to send is limited. My view is that what I gave him is what he can spare. At most he might be able to scrape one more division (to make the Reserve Corps into  two division corps).

For the Republic of Texas

Louis Wigfall was popular in Texas, and his proclamation of a Republic should attract many bitter-enders among the Confederate. However how many? Not that much. Let us think about Texas. In the total civil war it contributed about 70000 men to the Confederacy. So the yearly military potential of Texas as whole was abut 12-15000 men. Wigfall does not have all of Texas. He probably does not have even all of the ex-Confederates (many will detest a Mexican alliance). So 5000 seems like the maximum he could raise, and fits with the numbers of confederates that escaped to Mexico and Brazil after the war. My expectation would be that this force would be a primarily horse force.

For the Republic of Mexico (junta)

I went for an average between the forces of the regular Mexican Army after the war of reform and the forces raised by the Empire in history. This represents the part of the Mexican military that the French would consider as able to conduct large scale military operations. The number of 15-20k seems realistic. This excludes National Guard units.

Let us begin with potential dispositions of forces (click for larger map). Please ignore the rail lines on the map, as they did not exist in 1866.

The US Department of the Pacific will be headquartered in the San-Fransisco-Sacramento area.

Sheridan with the XXV corps will be at Galveston, while the IV Corps  is situated around San Angelo. Defending a line on the Colorado river. The two cavalry divisions (Custer/Merrit) are used to keep contact between them, and defned the IV corps northern Flank. The Three corps of the Army of the Gulf are situated in the triangle Vicksburg-Mobile-New Orleans.

The Army of the Republic of Texas is headquarted in El Paso (provisional capital) and probably engaged in skirmishing with either Custer or Merrit. The Army of the Republic of Mexico is staged at Chihuahua  close to the Rio Grande. Bazaine has the 1st and 2nd Corps of the French Army of Mexico situated along the Rio Grande towards he Gulf Cost. The Reserve Corps is situated partly in Mexico City and partly Vera Cruz.

Operational Plans: French

Considering the French minimalist goals, Bazaine needs to contest Texas or California from the US so that it can be used as a negotiating chip for US recognition of French predominance south of the Rio Grande. Operationally he must not let Sheridan link with the Army of the Gulf. This means that all must be done to lure Sheridan's corps away from each other, and away from the Army of the Gulf.  His goal would be to either place he army between Sheridan and the Army of the Gulf or, even better between the IV and XXV corps, defeating each in separate battles. Once he has dealt with Sheridan he can try to hold the Colorado river line and await negotiations.

So how does he try to lure Sheridan and still serve the political goal?

The map shows a possible French operational plan, and how they would expect or hope Sheridan would react. (click for larger map)

The Army of Mexio begins an ascent along the Rio Grande, hopefully luring the IV Corps after it. Its goal is to rich the Gila River and then follow it to invade California. The threat to California hopefully will force the IV corps to move East. 

At the same time the Army of Texas lunches a deep raid on the rear of the US lines with the goal of reaching Vicksburg and threatening lines of communications. Hopefully Sheridan sends either Custer or Merrit after them, weakening the IV corps. Potentially the XXV corps will advance in parallel with the IV  in order to cover its south flank. the Army of the Gulf will start concentrating its corps at Galveston, but too late to keep contact with Sheridan. Also some elements of XVI corps will have to be sent to Vicksburg due to the fear of the Texan Army.

The movements of the IV and XXV corps will hopefully create a gap that permits the 1st and 2nd Corps to interpose between them and force a battle at Bazaines choice somewhere north of the Rio Grande. At the very least the 2nd Corps should be able to interpose itself between the XXV corps and the Army of the Gulf. At the very least California will be invaded.

Or so go the hopes of the French.

A potential alternative is to have the Army of Mexico go up the Rio Grande, link with the Texans, and then hook right to try and outflank the IV corps. This provides more troops for Bazaine at the Rio Grande, but means California is not threatened, nor does IV corp lose a division. Indeed this plan might not force Sheridan to move enough.

Operational Plans:US

Like Bazaine, Sheridan also wants to finish this fast. He needs Bazaine to move, but he also would prefer to have at least one more corps at his hands. His main goal would be to control Texas, denying Napoleon III a negotiating chip, and forcing him to choose between a log war and defeat, or backing down now.

Sheridan expects an attempt by the Army of Texas to get at his rear, and that the Mexican Army will go for California. He will risk California, believing that the long march will weaken the Mexicans enough that US troops in the Pacific will be able to contain them.  His main decisions are two. He orders the XVI corps to risk a coastal move to join him at Galveston. until it arrives he keeps the Colorado River line, expecting that Bazaine will not assail it. In the meantime the XIX and XIII corps will make a large scale left hook and march through North Texas in the way negating any gains made by the Texans and finally holing them up at El Paso. Once that is complete the IV,XXV and XVI corps will march in parallel to the Rio Grande and seek a battle with the two French Corps. With 3 corps to 2 Sheridan believes he can give a bloody nose to the French.

Or so the Americans hope.

How does it go? Well this is where you the wargamers come in. After this point what happens is the subject of friction and thus gaming!

1 comment:

Steve J. said...

Excellent stuff once again.Looking forward to the next post and some OOB to try and give this a run out with Black Powder.