Here's some info about Ms. Carroll from the Maryland Women's Heritage Center:
Anna Ella Carroll is credited with helping to prevent Maryland’s secession from the Union, however, her involvement in the war was kept a secret from the public and the military for fear that Union generals and soldiers would not follow a plan devised by a woman civilian.
In fact, the 1864 painting of the First Reading of the Emancipation Proclamation of President Lincoln by Francis Carpenter depicting Lincoln and his cabinet prominently displays an empty chair filled with notes and maps, similar to the ones Carroll often carried. Many historians now feel it was Carpenter’s way of acknowledging Carroll, the unrecognized member of the cabinet.
Friends of Anna Carroll
A Military Genius: The Life of Anna Ella Carroll of Maryland by Sarah Ellen Blackwell, 1891.
Moses, The Monster, and Miss Anne (about Harriet Tubman, Patty Cannon, and Anna Ella Carroll)
The Anna Carroll historical marker
Who Planned the Tennessee Campaign of 1862?
* Note: The YouTube video above includes two scenes from “Lost River” and a third clip, starting about three minutes in, from “Lincoln’s Last Night.”
I'm sorry to say that I don't know where it will be showing beyond its premiere!