In the summer of 1861, Americans were preoccupied by the question of which states would join the secession movement and which would remain loyal to the Union. This question was most fractious in the border states of Maryland, Kentucky, and Missouri. In Missouri, it was largely settled at Wilson's Creek on August 10, 1861, in a contest that is rightly considered the second major battle of the Civil War.
In providing the first in-depth narrative...