The Mountain — David Lynn Golemon

A SHOCKING HISTORICAL SECRET HAS RESURFACED.
It's 1863. America's most legendary war leaders arrange a meeting ―a clandestine alliance that will never show up in any history book. Their mission: To heal a war-torn nation by bringing the remnants of a prized ship back to U.S. soil―one that may lie on a mountaintop inside the Ottoman Empire, where the men who seek it are only days away from killing one another. The battles will rage at sea and upon land―with enemies both past and future. Colonel John Henry Thomas of the Union Army will come face to face with his mortal enemies in the South and a dark entity that has been trapped on top of God's Mountain for a millennium.

CAN THE EVENT GROUP SOLVE ONE OF THE WORLD'S GREATEST MYSTERIES―AND SAVE THE FUTURE OF MANKIND?
In 2007, America's darkest agency, known to only a privileged few as the Event Group, recruits a man they desperately need for their security. Major Jack Collins is brought to the underground world of the organization to learn about the darkest secrets in history, and is told a tale that brings him full circle about his destiny and Department 5656. But what comes around goes around―and this time, there's no turning back…