General Wool and His Troops in the Streets of Saltillo, 1847

The anonymous daguerreotypist was almost certainly an American, one of several following the American troops through northern Mexico during the hostilities of 1846–48. The Americans called it the Mexican War. Many Mexicans still call it the US Invasion. The photographic process had been announced only a few years before, in Paris in 1839, and though improved technology rapidly decreased exposure times, in 1847 it remained impossible to capture a clear image of a moving object. Photography was ill-suited to capturing combat, or action of any sort. For good reason, the vast majority of daguerreotypes were studio portraits, made in carefully controlled conditions, with subjects tightly clamped into special stands to keep them motionless while the photographer exposed his plate. The photographers following the troops through Mexico were a ragtag bunch, without deep connections to American journalists or printers or consumers.