Liahona (City of the Saints #1) by D.J. Butler
1859; war looms over the United States. Intelligence agents converge on the Kingdom of Deseret in the Rocky Mountains. Sam Clemens, leading the U.S. Army’s expedition aboard his amphibious steam-truck the Jim Smiley, has a mission: to ensure that the Kingdom, with its air-ships and rumored phlogiston guns, brain children of the Madman Orson Pratt, enters on the side of the United States and peace. […]