What is the significance of Harriet Tubman?

Harriet Tubman was the conductor of the Underground
Railroad. Born a slave in Dorchester County, Maryland she later escaped in 1849 and made
her way to Philadelphia upon news that she was to be sold.  Later she returned to
Maryland to rescue her sister and her two children in 1850.  Throughout the next eleven
years, Tubman made 13 expeditions into the south and rescued 70 slaves.  Tubman made use
of free blacks, abolitionists and others in order to avoid capture.  She often sang
songs which were codes to alert the slaves she was present.  She was known to carry
chickens or other goods so that she appeared to be a slave woman conducting errands. 
About her years rescuing slaves she stated "I was conductor of the Underground Railroad
for eight years, and I can say what most conductors can't say – I never ran my train off
the track and I never lost a passenger."

During the Civil
War Tubman served the Union Army as a nurse, spy, and a scout.  She helped conduct a
raid during the war that freed as many as 750 slaves.  She later settled in Auburn, New
York and attempted to establish a home for destitute former slaves who were too old to
work.  She died in 1913.