Sarah Emma Edmonds (later Seeyle) dressed up a man and fought as a soldier in the American Civil War. She later wrote a book about her experiences, titled "Nurse and Spy in the Civil War," where she detailed her many dangerous adventures behind enemy lines.

Going a step further than Mulan, Edmonds, while pretending to be a man, then pretended to be other people including slave men and women and an old Irish peddler woman to spy on the Confederacy in an identity crisis that would make Tropic Thunder blush.

To read more about her, Karen Abbott covers Edmonds and three other daring Civil War women in the book "Liar, Temptress, Soldier, Spy: Four Women Going Undercover in the Civil War."

Sources: Karen Abbott "Liar, Temptress, Soldier Spy: Four Women Going Undercover in the Civil War." - Jerome Robbins diary entries quoted in this source.

Sarah Emma Edmonds "Nurse and Spy in the Union Army"