The Civil War.

https://en.wikipedia.org/wiki/Mary_Louvestre

https://www.lib.umd.edu/civilwarwomen/womens-histories/free-black-women

https://www.aaihs.org/black-women-agency-and-the-civil-war/

http://msmagazine.com/blog/2011/02/28/the-brave-black-women-who-were-civil-war-spies/