The winter of 1451 was one of the coldest in Europe. The continent was still in the clutches of a mini ice age that had lasted for nearly a century and had left famine, disease, and the dreaded Black Death in its path. It had also brought in hungry invaders and marauders from central Asia in search of food and warmth. These ravenous intruders followed the path of their great ancestors, the Mongolian hordes of Genghis Khan, who had ravaged Russia and the Middle East two centuries earlier, except this time around they cast their eyes further into conquering the whole of Europe. The mightiest of...