YaATW2KT: The Second Mexican-American War

[StainlessSteelCynic]

On a side note, I've been trying to get better info on those Argentinian upgraded Shermans.
Even looking through Jane's for the relevant years there's not a lot of information but I do have the following for the powerpack that was used.

Paraphrasing from Jane's Armour and Artillery 1986-87, page 950

Poyaud 520 series engines developed to a requirement of the French army although weren't used by the French army. Based around a common cylinder of 135mm bore and 122mm stroke. The modular construction of the engines allowed them to be offered in many configurations for many different vehicles (including Soviet) chiefly naturally aspirated (NS suffix), turbo-charged (S1 suffix), turbo-charged with charge-air intercooling (S2), turbo-charged with oil-cooled pistons and intercooling (S25) and turbo-compounded using the "Hyperbar" process (S3).
All variants were apparently direct injection and water cooled.
It seems as though the engines could be supplied to a buyer in kit form for assembly at their point of destination.

The Argentinian upgraded Shermans were fitted with the 520 V8 S25, meaning they used the turbo-charged, oil-cooled piston, intercooler version. This developed 2500rpm at 570HP (420kW). It looks as though this engine was designed for US vehicles of the post-WW2 era e.g. M4 Medium, M36 and M41.

I haven't found anything to state these were petrol/gasoline or diesel except for the article I originally linked. I'm inclined to think diesel because they were all direct-injection but that's just a guess. I'm hoping someone with a better knowledge of engines than me (which pretty much means just about everybody!), can make a better assessment of that.
What all of that means for game stats I'll leave (again!), to people with a better understanding of engines.

I haven't found anything specific about the 105mm gun except for the article I linked that states it was a French gun. Given that the French had tested a 105mm on the AMX13, they certainly would have had the tech knowledge for designing one suitable for refitting to the Shermans.

[The Dark]

Originally Posted by StainlessSteelCynic

On a side note, I've been trying to get better info on those Argentinian upgraded Shermans.
Even looking through Jane's for the relevant years there's not a lot of information but I do have the following for the powerpack that was used.

Paraphrasing from Jane's Armour and Artillery 1986-87, page 950

Poyaud 520 series engines developed to a requirement of the French army although weren't used by the French army. Based around a common cylinder of 135mm bore and 122mm stroke. The modular construction of the engines allowed them to be offered in many configurations for many different vehicles (including Soviet) chiefly naturally aspirated (NS suffix), turbo-charged (S1 suffix), turbo-charged with charge-air intercooling (S2), turbo-charged with oil-cooled pistons and intercooling (S25) and turbo-compounded using the "Hyperbar" process (S3).
All variants were apparently direct injection and water cooled.
It seems as though the engines could be supplied to a buyer in kit form for assembly at their point of destination.

The Argentinian upgraded Shermans were fitted with the 520 V8 S25, meaning they used the turbo-charged, oil-cooled piston, intercooler version. This developed 2500rpm at 570HP (420kW). It looks as though this engine was designed for US vehicles of the post-WW2 era e.g. M4 Medium, M36 and M41.

I haven't found anything to state these were petrol/gasoline or diesel except for the article I originally linked. I'm inclined to think diesel because they were all direct-injection but that's just a guess. I'm hoping someone with a better knowledge of engines than me (which pretty much means just about everybody!), can make a better assessment of that.
What all of that means for game stats I'll leave (again!), to people with a better understanding of engines.

I haven't found anything specific about the 105mm gun except for the article I linked that states it was a French gun. Given that the French had tested a 105mm on the AMX13, they certainly would have had the tech knowledge for designing one suitable for refitting to the Shermans.

The Poyaud 520 is a V-8 diesel engine. The Sherman Repotenciado's gun was a license-built version of the 105mm from the AMX-13, the coax was a MAG-58, and the pintle MG an M2HB. Many of them were rebuilt Sherman Firefly, since England repaid some of its debt to Argentina by giving them Shermans at scrap metal cost. To make room for the gun upgrade and increased shell size, it had no radio operator (not a big deal with modern radios) and no loader (big deal, since it didn't have an autoloader). It's not really relevant to this discussion, but a lot of the Shermans in Saving Private Ryan were Repotenciadoes.

Paraguay is (or was, as of 2015) still using three of them as ceremonial vehicles for the Presidential Escort Regiment. The three in use are SN 15919 (built by Baldwin in September 1943), SN 40351 (built by ALCO in November 1943), and SN 6057 (built by Chrysler in November 1942).

There were also Chilean Shermans (which Paul has listed under the Israeli tanks, since they're modified Israeli Shermans). They bought Israeli M-50 and M-51 Shermans and re-engined them with Detroit Diesel 8V71T engines. The M-51 (105mm) was kept with its existing armament, but the M-50 (75mm) was re-armed with IMI's 60mm HVMS cannon (which was also used in Chilean Chaffee tanks).

[StainlessSteelCynic]

Update re: Argentina's upgraded Shermans. And I've just noticed The Dark posted while I was compiling all this!
According to the following site, the French 105mm gun was the CN-105-57 L/44
https://aw.my.com/us/news/general/et...-years-sherman
Right down but not quite the bottom of the page.

Some more info that may or may not be helpful because the poster has English as a secondary language and his translations are a little tricky to understand for me (being unfamiliar with the way Spanish grammar works). Lots of images though including photos of operating Shermans in the celebration parade of Argentina's 200 years of independence (2016 I believe).
http://tank-encyclopedia.org/Forum/s...2366&pid=46838

This page has some more info and states that the crew was reduced to just three men.
https://m.facebook.com/TheArmorJourn...28587243927757

Some minor history of three upgraded Shermans given by Argentina to Paraguay but mentions the new tracks fitted to the tanks (T49 type track and drive sprocket). What this means for game stats regarding speed, travel move and so on I'll leave to wiser heads than mine.
http://www.blitz72.com/2012/01/parag...erman-firefly/

Model vehicle site with some extra info, specifically new radio gear and auxillary fuel tank. Speculating on my part, guess that means fuel economy is not much better than original Shermans?
http://www.track-link.com/gallery/5133
http://www.track-link.com/gallery/4169

Even if the lower number is used for the total number of upgrades (120 versus 250), that still leaves a healthy number of 105mm gunned tanks if we're going to use them to bolster Mexican forces. Some idle speculation: if the three-man crew is accurate, that would also fit into the idea of early initial success for Mexican forces (when the Sherman force is at full strength), but later they aren't so effective as they suffer attrition and extended supply lines and therefore making the surviving three-man crews have to carry more of the burden.

Edit: According to the following site, the French 105mm had an auto-loader hence a human loader was not required. Right down the bottom of the page, under the image of the Sherman with the Argentine flag flying behind it.
http://the.shadock.free.fr/sherman_m..._variants.html

[The Dark]

Originally Posted by StainlessSteelCynic

Edit: According to the following site, the French 105mm had an auto-loader hence a human loader was not required. Right down the bottom of the page, under the image of the Sherman with the Argentine flag flying behind it.
http://the.shadock.free.fr/sherman_m..._variants.html

Good catch on this. I knew the AMX-13 had an autoloader, but none of the sources I found mentioned one in the Argentinian Shermans. That would make the Shermans a bit more useful, since it would give them a much better rate of fire with a gun capable of defeating M60 frontal armor at 2+ kilometers.

[StainlessSteelCynic]

Originally Posted by The Dark

Good catch on this. I knew the AMX-13 had an autoloader, but none of the sources I found mentioned one in the Argentinian Shermans. That would make the Shermans a bit more useful, since it would give them a much better rate of fire with a gun capable of defeating M60 frontal armor at 2+ kilometers.

The Argentine Shermans are an interesting branch in armoured vehicle history and one that I'd never really heard much about before. It really caught my curiosity so I spent an entire evening typing into the search engine any combination of Argentina, Sherman, upgrade and tank! Perhaps I was a little obsessed

I really expected Janes or at least Bart Vanderveen to have some reference to them (Vanderveen made a lifetime hobby for many people out of his own interest in military vehicle history) but none of Vanderveen's Wheels & Tracks magazine I checked had any mention and Janes was minimal at best (with most of the relevant info being found in the Armour & Artillery yearbooks for 1986-87 and 1987-88 yearbooks).
I was surprised by Vanderveen' lack of info as his Historic Military Vehicles Directory (compiled from Wheels & Tracks in 1989) includes the Argentine DL43 Nahuel Medium tank which was itself ousted by Shermans but no mention of the upgraded Shermans.
This is one time when the internet really put the books to shame.

It was fascinating to read the background and history but also to see that Argentina (and Paraguay too) still had some in operating condition into the 2000s where they were using them to test a new mine plough (and of course, having them feature in the 200th anniversary parade).

[RN7]

A list of major U.S. units in the southwest in 2000 by pre-war composition. This would exclude some additional units attached to corps HQ's, and also army helicopter units which are likely to be grounded due to a lack of fuel. This does not include current losses from combat, attrition and other factors.

49th Armored Division: Oklahoma
2 M1A1 battalion
2 M1 battalion
1 M60A3 battalion
1 M113 CAV battalion
2 M2 battalion
2 M113 battalion
1 MLRS battalion
3 SP 155mm battalion
1 M998 Roland AD battalion

40th Infantry Division (Mechanised): California (2 brigades only)
2 M1 battalion
2 M60A3 battalion
1 M113 CAV battalion
2 M2 battalion
4 M113 battalion
1 MLRS battalion
3 SP 155mm battalion
1 M998 Roland AD battalion

46th Infantry Division: California
1 M60A3 battalion
2 M113 battalion
7 Light Motorized battalion
1 MLRS battalion
1 SP 155mm battalion
2 Towed 155mm battalion
1 M741 Chaparral AD battalion

85th Infantry Division (Light): Louisiana (1 brigade only)
9 Foot Infantry battalion
3 Towed 105mm battalion

91st Infantry Division (Light): California9 Foot Infantry battalion
3 Towed 105mm battalion

95th Infantry Division (Light): Oklahoma
9 Foot Infantry battalion
3 Towed 105mm battalion

98th Infantry Division (Light): Louisiana (1 brigade only)
9 Foot Infantry battalion
3 Towed 105mm battalion

100th Infantry Division (Light): Colorado
9 Foot Infantry battalion
3 Towed 105mm battalion

45th Field Artillery Brigade: Oklahoma
3 Towed 155 or 105mm battalion

65th Field Artillery Brigade: Utah
3 Towed 155 or 105mm battalion

153rd Field Artillery Brigade: California/Nevada
3 Towed 155 or 105mm battalion

169th Field Artillery Brigade: Colorado
3 Towed 155 or 105mm battalion

6th Air Defence Artillery Brigade: Oklahoma
3 M998 Roland or M741 Chaparral AD battalion

111th Air Defence Artillery Brigade: Colorado/New Mexico
3 M998 Roland or M741 Chaparral AD battalion

49th Military Police Brigade: California
Light motorized or foot infantry only

221st Military Police Brigade: California
Light motorized or foot infantry only

225th Engineer Brigade: Louisiana
Light motorized infantry with some engineer vehicles

Cadet Brigade: Colorado
Light motorized or foot infantry with a few tanks, AFV and air defence vehicles

School Brigade: Oklahoma
Light motorized or foot infantry only

10th Special Forces Group: some units Colorado
Company sized light motorized or foot infantry only

19th Special Forces Group: some units in Utah
Company sized light motorized or foot infantry only

[Raellus]

RN7, I'm not clear on your source for those figures. IRL, a lot of those units existed only on paper. According to the U.S. Army Vehicle Guide, some them had attached armor, for example, the 95th LID lists some M60s but your list omits these. Is it a hybrid list? (i.e. part RL, part canon) I hope I don't sound cranky, because I'm not. Just curious.

[Raellus]

I'm trying to come up with a concept that will unify the ideas upon which the Mexican invasion and subsequent occupation of the American Southwest are predicated on. Here's what I've come up with.

Suppositions:

• In a alternate timeline (v1.0 is the way to go, IMHO), NAFTA doesn't happen, or if it does, in a somewhat modified format.
  
• Oil markets are bullish and Mexico receives an influx of petro-dollars.
  
• Mexico has to deal with a resurgent insurgency in its southern states. Fairly or not, Guatemala is accused of collusion with the guerillas.

Ergo:

There is a minor trade dispute with the U.S. Not enough for either nation to feel threatened by the other, but enough to make them both grumpy with one another.

Instead of taking a progressive approach, spending those petro-dollars on building badly-needed infrastructure and helping the impoverished peasants that support the rebels, the Mexican government, succumbing to pressure from its military establishment, decides to spend the money on armaments instead, so that it can finally "pacify" the restive southern states.

Because of the trade dispute with the U.S., Mexico conscientiously decides not to buy American. But because of American diplomatic clout, they can't buy current generation armor (and the Mexican government isn't foolhardy enough to try to buy Soviet). So, they look to buy used from non-aligned nations. France is upgrading its MBT fleet from the AMX-30 to the Leclerc, so Mexico approaches the French to buy retired AMX-30s. The French aren't necessarily non-aligned, but they always try to do their own thing, so they agree to sell the Mexicans a regiment's worth of AMX-30s, and to throw in a bunch of retired AMX-13s as well. A deal is struck.

OR

Mexico and Argentina broker a deal for the former to purchase a fleet of new-build TAM tanks from the latter, and Argentina offers to throw in its upgraded Shermans to sweeten the deal.

AND (regardless of which of the two above alternatives you select)

In the meantime, Mexico looks into upgrading its existing armor force. It makes a deal with Brazil for the latter to upgrade its fleet of M3 Stuarts to the X1 status. Brazil offers to sell some of its own upgraded fleet of X1A-2s to Mexico as well. A preliminary agreement to buy some Brazilian EE-11 Urutus and EE-9 Cascavels is reached as well.

This unified theory explains some of the tension between Mexico and the U.S. and justifies/explains Mexico's acquisition of non-American AFVs in the run up to the invasion.

[RN7]

Originally Posted by Raellus

RN7, I'm not clear on your source for those figures. IRL, a lot of those units existed only on paper. According to the U.S. Army Vehicle Guide, some them had attached armor, for example, the 95th LID lists some M60s but your list omits these. Is it a hybrid list? (i.e. part RL, part canon) I hope I don't sound cranky, because I'm not. Just curious.

Its a bit of a hybrid list.

The divisions and some of the recognisable known brigades are canon from the composition of army divisions and selected non-divisional units list in the American Combat Vehicle Handbook 2nd edition. Just basic pre-war organisation to show what type of equipment these units would likely be using in 2000. None would be at any way near full strength.

The other artillery and AD brigades are regional based National Guard brigades that are likely to have remained behind in the area after regular army artillery and AD brigades from the southwest were sent overseas or elsewhere. The two special forces groups were also regional based and a company or two from either unit are likely to be still in the region. I gave each brigade 1 battalion of artillery or SAM's instead of 3. I'll change that.

GDW does list the 95th ID having 3 M60A3, but it was still a light infantry division.

The 98th light infantry division also had 4 M60A3, and the 100th light infantry division had 1 M1A1, 1 M1 and 4 M60A3.