1. Standing Firmly by the Flag: Nebraska Territory and the Civil War, 1861-1867 by James E. Potter (Bison, 2012).
This project started out as a regimental history of the First Nebraska (that would have been cool) but morphed into a more general study. Too bad the author didn't feel he could do both. Breaking it into two books would have been great. Then again, I should just be happy that someone tried to tackle this subject at all.
2. Major General Alexander M. McCook, USA: A Civil War Biography by Wayne Fanebust (McFarland, 2012).
A military biography of the lightly regarded McCook, based on published sources.