One of the most celebrated heroines in American history, Harriet Tubman is best known for ushering slaves to freedom through the Underground Railroad in the 1850s. But not everyone knows that Tubman, who escaped slavery in 1849, set up a vast espionage ring for the Union during the Civil War. She served as a cook, a nurse, and even a spy for the Union during the Civil War, and also was the first woman in American history to lead a military expedition.

In one of her most dramatic and dangerous roles, Tubman helped Colonel James Montgomery plan a raid to free slaves from plantations along the Combahee River in South Carolina. Early on the morning of June 1, 1863, three gunboats carrying several hundred male soldiers along with Harriet Tubman set out on their mission. Tubman had gathered key information from her scouts about the Confederates' positions, and knew where they were hiding along the shore. She also found out they had placed torpedoes -- barrels filled with gunpowder -- in the water. Ultimately, her group freed about 750 slaves -- men, women, children, and babies -- and did not lose one soldier in the attack. Reporting on the raid to Secretary of War Stanton, Brigadier General Rufus Saxton said, "This is the

only military command in American history wherein a woman, black or white, led the raid, and under whose inspiration. it was originated and conducted." Sadly, Tubman was paid only $200 during her three years of service and was denied a pension for her spy work.