The Mongols formed one of the finest armies ever known--and when they swept across the Danube on Christmas Day 1241, the west lay at the mercy of these "horsemen from hell." From a wealth of contemporary sources comes the story of these soldiers, and especially of Subedei Bahadur, the illiterate military genius who brought 20th-century warfare to Medieval Europe. A fascinating examination of their tactics and training--good enough to invent strategies that Rommel and Patton would later use to such devastating effect--proves the Mongols were more than mere barbarians: they were martial masterminds of the highest order.