Army of the Dead by Joseph Conti

3.20

In 1590, Coronado dispatched a division of one thousand men to find El Dorado, the legendary city of gold. Those men were never seen again. While searching some Baja peninsula caves as part of an archeological expedition, a university professor and his students unwittingly unleash a long dormant curse. They soon find themselves in a life or death battle with an army of skeletal warriors, the undead remnants of Coronado's conquistadors.