Born a slave, Harriet Tubman was a Union nurse and spy during the Civil War. While volunteering for the Union Army she was recruited by Federal officers to set up an espionage network in the South, making her the first woman in U.S. history to lead a military expedition. In 1863 she planned a night raid and led several hundred black soldiers up the Combahee River in gunboats. They destroyed Confederate supply depots and freed more than 750 slaves. After the war Tubman tried without success to collect the money owed her for military service in the Federal Army.