Americans so love to fantasize about being underdogs that the fall of the Alamo has been filmed more than a dozen times, though John Wayne’s legendary 1960 fiasco and a more enlightened political climate have made it a dicier prospect in recent years. This Disney epic, conceived by Ron Howard but handed over to director John Lee Hancock (The Rookie), indulges the flag-wavers, but its chronicle of the politics behind the Texans’ 1835 defeat and subsequent victory at San Jacinto is more thoughtful and complex than I anticipated. A shapely and intelligent script by Hancock, Leslie Bohem, and Stephen Gaghan notes the cruelty of Mexican general Santa Anna but also the American settlers’ imperial lust, and its Davy Crockett (Billy Bob Thornton in his best role since Sling Blade) is both embarrassed by his own myth and haunted by the Indian slaughter that nurtured it. With Dennis Quaid as Sam Houston, Jason Patric as Jim Bowie, and Patrick Wilson as William Travis. PG-13, 137 min. Century 12 and CineArts 6, Chatham 14, Crown Village 18, Ford City, Gardens 7-13, Golf Glen, Lincoln Village, Norridge, North Riverside, River East 21, Village, Webster Place.