The American army deployed.
Starting small and starting at the beginning both seemed smart and both led me to Palo Alto. Luckily, I just happened to have kept some old Courier articles on the war and one was this very battle. Having previously cross checked it against a few other sources, this is not a war that I am "into" but it is "in period" and I like the US uniforms, so I have a few books and articles squirreled away and websites marked.
Apart from lacking a few gunners, I have more than enough American infantry and dragoons to do Palo Alto using 10 infantry or 4 dragoons per unit. Until I rebase though, I can't fit that many in a hex so most units are 8 while I only used 2 Dragoons per squadron to avoid embarassing the supposedly more numerous Mexican cavalry who were only able to fit 2 figures in a hex.
The Mexicans are more problematic, I don't have any 1840's Mexicans and like the earlier uniforms better anyway. My one 24 man Mexican unit broke down into 4 6 man units and 1812 American infantry wearing Blue coats and shakos filled in for the rest. The British supplied gun crews and cavalry while New York filled out the cavalry ranks.
This is what I call a Mexican Stand In.
Each unit represents somewhere around 400 infantry, 100 cavalry or 4-6 guns. Perhaps I should have halved the number of cavalry stands but it worked well enough.
I used the modified Quality/Effect die roll that I suggested but left all other rules alone, except for details of unit capabilities. This was a war where units on opposing sides were not always equal. The Mexican troops were brave but suffered from leadership and equipment issues with obsolete weapons, poor powder and so on. After some thought I decided on the following troop capabilities:
US Infantry: Regular Infantry, Muskets, no special rules
US Dragoons: Elite Cavalry, no special rules.
US Artillery: Elite Artillery, Moves 2 hexes instead of 1, Melee value of 3/6
(a little more Grape Captain Bragg, crack troops armed with light 12 pounders and 18 pdr howitzers, horse artillery really.)
Mexican Infantry: Regular Infantry, Muskets, -1 to all shooting dice
(due to old muskets and poor powder.)
Mexican Regular Cavalry: Regular Cavalry, Melee value of 3/6
(due to performance and smaller horses)
(Note: I just realized that I inversed the irregular and regular cavalry values when I originally typed this up. The red figures are corrected)
Mexican Irregular Cavalry: Militia Cavalry, Melee value of 4/6
(these were really bandits rather than soldiers and of little use in pitched battle)
Mexican Artillery: Regular Artillery. -1 to all shooting dice. Melee value, 5/6
(armed with old ox drawn 4 pounders and poor powder)
I ruled that it cost 2 movement points to enter a hex of chapparrell. Cavalry attacking through chapparrell would have a +1 penalty to their Melee Value. (it belatedly occurred to me that -1 for fighting enemy in chapparell would be better, reducing the effect of the troops struggling through the brush rather than increasing their risk.)
Once fighting was engaged, the historical brush fire would be simulated by having a turn with no shooting or melee allowed and giving the Mexicans a free move to start their redeployment.
Not being a campaign game, I decided that the first side to lose over 1/2 if their original units would retreat. The Mexicans had 7 infantry, 3 guns and 11 cavalry and could afford to lose 10 units. The Americans had 5 infantry, 3 guns and 2 cavalry and could afford to lose 5 units. Both sides had a general for looks only.
Both armies would follow their original battle plans as far as possible given that I only had the general idea, an exchange of artillery fire, Mexicans counter-battery without effect, Americans counter infantry with effect, followed by an attack by Mexican cavalry on their left supported by guns and infantry through the brush on the left, then the fire and redeployment and an attack up the right by the irregular cavalry supported by infantry.
Casualty figures and unmanned guns mark where units were destroyed.
The first stage went according to plan with one Mexican battalion being destroyed and another forced to recoil. The attack through the Chapparrell started off historically with heavy losses from the US infantry but 1 squadron managed to charge and take out Ringgold's elite horse artillery. ( A 6 in melee followed by a 1 for effect...Oops! dice! What can you do? ). I committed the US dragoons and then called the brush fire. 6 out of 8 Mexican squadrons had been destroyed in addition to the infantry lost to artillery fire earlier. The Americans had lost a gun and an infantry. Honours almost even but slightly in the US favour.
There were lots of Indian soldatos in the Irregular Lancers right? Oh. Not that kind?
The flanking attack by the Irregular cavalry looked dangerous until it got close. I decided to throw in the reserve and launch a major infantry attack at the same time. Units were forced back or destroyed on both sides with the Americans losing another battery (ouch!) and a battalion. This brought them to 4 losses, 2 away from breaking. The Mexicans however, lost 1 of the Irregular cavalry and no less than 3 infantry, mostly to artillery fire.
History repeated itself and they fell back towards Resaca de la Palma.
The game took a little over an hour to set up and play but it is one of the smallest American-Mexican battles and it was a fun little game with some tense moments. At first I pondered why the Mexicans let 1/2 their army sit while one wing attacked and then did the same on the other side. PW1's activation die might have supplied a reason to emulate it if not a reason it happened but then I realized that my 50% scenario army morale provided ample reason. An unsuccessful and bloody assault on 1 wing might have upped the casualty total fast enough that the game could be lost despite a bloody but successful attack on the other wing. So the rules worked well as is. (I consider my troop capability decisions to be campaign qualifiers not rules changes)
The historical result came naturally but it was close enough that it could have been reversed, especially if played by 2 players and no constraints on tactics. If I get a chance though, I may try it again with Morschauser Meets MacDuff, the proto-version of Hearts of Tin.