The Bonnie Blue Flag! is a decision for 
Confederate States of America during the American Civil War. The name is a refence to a confederate Marching Song from the Civil War.
It requires that CSA is at war with 
USA, but it doesn't strictly speaking has to be the civil war. It can be used at a later war. There are no other requirements.
It creates the two legendary southern states generals Robert E.Lee (Audacious, War College) and Thomas Stonewall Jackson (Coolminded, School of Defense). Those two are some of the best traits generals can have in the game.
On top of that it gives 2 leadership pr. month, 10% mobilization size and -25% mobilization impact for 1 year.
It is not possible to take in the 1861 starting date, as CSA already starts with the two generals commanding armies.
In-game text
Hurrah! Hurrah! For Southern Rights Hurrah! Hurrah, for the Bonnie Blue Flag that bears a Single Star! The Bonnie Blue Flag was the first official flag of the Confederacy, and also the name of a popular 1861 marching song by Harry McCarthy praising that same flag. Hoist the Bonnie Blue, and watch the recruits flock to our banner.