The Battle Hymn of the Republic — Jack Martin

The Civil War has ended -- but the killing isn't over -- in this intriguing historical murder mystery: “I can't wait to read the next Alphonso Clay book.” -- RP Dahlke, author of the Dead Red Mysteries
 
April 1865: The Civil War is all but over after Lee's surrender at Appomattox, but there are those who don't want the killing to end. Abraham Lincoln's assassin is still in hiding -- but more violence is planned in a conspiracy to destroy the country once and for all.
 
With the nation and countless civilian lives at stake, Col. Alphonso Clay, a master of intrigue and detection who has served General Grant with honor, is assigned to the case by the secretary of state. With the help of a beautiful agent, he is about to travel into the destructive heart of a secretive cult older than the United States itself . . .