I got this from the cart of free books at my local library, where I often find good books I otherwise wouldn't have read. I read it in one sitting; it's only 102 pages. I picked it because it's short—I'm a few weeks behind in my 2018 book-a-week project—and I haven't read enough about the Civil War.
It tells of the first major battle, through the eyes of about a dozen different characters, who come from both sides of the war. They give brief monologues describing their experiences and feelings before, during, and after the horrific fighting.
There's a light-skinned African-American who passes for white so he can join the Union army, where he encounters appalling racism. There's an 11 year-old boy who pretends he can play the fife because he wants so badly to kill Yankees but is too young to fight. (When he sees the aftermath of the butchery, he is a frightened child again.) My favorite was a German infantryman, an orphan, whose only human connection was a note from a woman he'd never met.
No-one, other than a fatalistic doctor, is prepared for the gruesome carnage. The overall impression is of ordinary people, doing what's expected of them, as though war were some huge social event everyone must attend. Little do they know they are unchaining ravenous demons that will not be put back in their cages until they have torn limb from limb the guilty and the innocent alike, for 4 years that will seem like an eternity. The Battle of Bull Run/ Manassas was a shocking blow to the innocence of ordinary Americans. As it will be if it happens again.
It's a quick read and well worth it.