In 1845 the seccession from Mexico of the territory of Texas, and its subsequent annexation by the United States, was to spark a bitter conflict. The war was to rage throughout California and northern Mexican territory for months, with neither side gaining the upper hand. However, the Battle of Monterrey was to see the tide begin to turn decisively in favour of US forces.
Initially unable to penetrate the walls of the numerous Mexican fortifications around the town, US commanders, increasingly-desperate to secure a morale-boosting victory, were to bring the newly-developed B17 "Walking Fortress" into the fray. Although untested and ponderous, the B17 was to prove practically unstoppable. Armed with chain-driven ripsaws and Gatling Cannons, they were to breach the walls with relative ease, inflicting horrific casualties on the Mexican defenders and creating a terrifying reputation.
Further photographs of this fearsome engine of war, many in colour, may be viewed here.