The Story the Soldiers Wouldn't Tell: Sex in the Civil War by Thomas P. Lowry, MD, is a quasi-academic history of exactly what it says in the title, free courtesy of publisher Stackpole who've given us a number of nifty military histories in the past.
Free @
Amazon (not available to Canadians). Unlikely to show up elsewhere, as previous Stackpole freebies have been Amazon-only.
Description (frankendescription cobbled together from the e-book and hardcover versions of the blurb, both of which are not particularly good, but at least the editorial reviews give you decent detail)
First book to cover all aspects of sexuality during the Civil War. Based on area original sources, including the soldiers' jokes, songs, letters, and diaries.
Explores the secret life of the men in blue and gray--from pornography, bawdy songs, and prostitution to stories of love and marriage