Women dressed as men so they could be soldiers in the Civil War

And they fought like demons

In They Fought Like Demons: Women Soldiers in the Civil War (public library), historians DeAnne Blanton and Lauren M. Cook chronicle and contextualize more than 250 documented cases of women who served in the ranks of both the Union and Confederate armies dressed as men

Thanks to Maria Popova over at Brain Pickings for posting this, and to my wonderful wife for pointing it out to me.