Harriet Tubman is considered one of the most heroic people in American history.Born Araminta Ross, or Minty, Tubman was an abolitionistand political activist, and fought in the American Civil War.But across America, Tubman is best known for rescuingmore than 70 enslaved people through a system called the Underground Railroad.And now, a new film tells her story.Harriet is the first full-length film about Tubman's life.It opened last week in theaters across the United States.For many people who know only children's book stories about Tubman,Harriet offers a more detailed story of the woman known in her day as the Moses of her people.Moses was a biblical leader who led his fellow Jews out of slavery.The film Harriet centers on Tubman's escape from slavery in Marylandin 1849 and the rescues that led so many enslaved people to freedom.Cynthia Erivo plays Tubman.She said stories that present Tubman as an older woman do not give a complete picture."It is important to know this was a really young womanwho took a lot of risk in what she was doing," Erivo said.Harriet director Kasi Lemmons said she was moved to make the filmafter the recent discovery of a photo of Tubman."There was this very small, young womanwho managed to do incredible things," said Lemmons.The picture was believed to be taken in the 1860swhen Tubman would have been in her early forties.Earlier this year, that picture was on show at the Smithsonian National Museumof African American History and Culture in Washington, D.C.Today, many Americans still only have basic knowledge of Tubman's life.Some do not know, for example, that she servedin the Union Army as a spy during the American Civil War.In 1863, she led 150 black soldiers on a gunboat raid in the state of South Carolina.The raid freed more than 700 enslaved people.Tubman also became a leader in the fight to establish voting rights for women.She was in her early 90s when she died in 1913.Efforts to make a full-length movie about Tubmanhave been discussed for several years.But Lemmons said her project came to life when she found Erivo.But Erivo is British, not American,and some people are displeased by Lemmons' choice as a result.Erivo, however, believes there are common experiencesbetween black people of both countries.Director Kasi Lemmons says Tubman herselfwas the spiritual guide of the movie's production."I really thought about this as... Harriet to lifeso that young girls could see this young woman heroine,and that the world could see her as this fierce, strong,feminine presence that she was," Lemmons said.Harriet earned $12 million from movie goers last weekend.The website Metacritic reports the film received generally favorable criticism.