I like the idea. As a native of Texas, I've always enjoyed the story of the Alamo, so to be able to play it on a CC map would be cool.
I'll echo Koontz in saying that the colors need to be muted quite a bit. Also with the territ/border lines. They look pretty bad. Especially the ones bordering the river, they're very pixelated/jagged and could use some cleaning up.
Any particular reason why Davy Crockett is outside of the Alamo? On the same note, why is Santa Anna in the North Plains and not in one of the Mexican Army areas?
Also, what's up with the river/s? Is that how the river actually is? I know there is a river near the alamo, because of the River Walk down in San Antonio, but I'm not all that familiar with the layout. Is your depiction of it fairly accurate? It just seems a bit odd is all...
Nice first draft(s).