Abolitionist Harriet Tubman led many enslaved people to safety via the Underground Railroad.
CNN  — 

From when the first ship carried Africans to the shores of Virginia in the early 1600s until 1865, when the 13th Amendment was officially ratified, millions of people were enslaved.

And among those millions was Harriet Tubman.

More than a dozen times in her life, she sacrificed her freedom to travel back to Maryland where she had escaped. And by doing so, she changed the course of American history.

Since 1990, the US celebrates her achievements on March 10 – Harriet Tubman Day.

Here’s a timeline of a remarkable life.

1820-1822: Tubman’s story begins

Although the exact date of her birth is unknown, historians agree that her story begins in Dorchester County, Maryland, around 1820-1822. Her parents, Ben Ross and Harriet Green, named her Araminta.

She was one of nine children born into slavery, but most of her siblings were sold to distant plantations. Tubman changed her name more than 20 years later in honor of her mother.

1833-1836: Tubman’s teen years

While in her early teens, Tubman’s fight for justice became apparent. She took a blow to her head and was nearly killed when she stepped between a slave who left a field without permission and an overseer, according to History.com.

Tubman continued to have seizures and severe headaches throughout her life because of the gruesome injury.

1844: Tubman’s first marriage

Harriet married John Tubman, a free African American, in 1844. Little is known about how the two met, but it wasn’t unusual for a free and enslaved couple to be married. About half of the African American population on the Eastern Shore of Maryland was free at the time, according to Biography.

Tubman adopted her husband’s last name and her mother’s first name, meaning she was now referred to as Harriet Tubman. She and her husband separated years later when he refused to join her escape.

1849: Tubman’s escape

Tubman and her two brothers decided to escape the plantation and head to Pennsylvania in 1849, when their owner passed away and they feared they would be sold. Her brothers became frightened and turned back.

Tubman safely arrived in Philadelphia, although $100 was offered for her capture, according to the National Park Service. “I had crossed the line. I was free; but there was no one to welcome me to the land of freedom. I was a stranger in a strange land,” she would later say.

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1850-1860: The Underground Railroad

Tubman was never content with being free unless everyone else was, too. She vowed to return to the plantation and bring her family and friends to freedom. And for the next 10 years, she made more than a dozen trips to Maryland to free slaves, according to the National Park Service.

She made her first trip back in 1850, when she discovered that her niece, Kessiah, was going to be auctioned off. First, she came up with a plan with Kessiah’s husband, a free man. Then, she guided them through the Underground Railroad, a secret network of routes and safe houses, after he bought his family at the auction, according to Biography.

Tubman used the skills she learned while observing the stars and working in the fields and woods to guide people to freedom. She also gave instructions to slaves who eventually found their way to freedom. She later claimed to have never lost a passenger on the Underground Railroad.

And when Congress passed the Fugitive Slave Act of 1850, which allowed authorities in non-slave states to capture and return escaped slaves to their owners, Tubman helped reroute the Underground Railroad to Canada.

She took her last trip to Maryland in 1860. While some say Tubman rescued 300 people during her trips, the Harriet Tubman Underground Railroad Byway puts the number closer to 70.

1859: Tubman’s first home

Tubman purchased her first piece of land in Auburn, New York, from Sen. William H. Seward in 1859. She spent the rest of her life there, the National Park Service says.

She welcomed her friends and family to stay with her while they settled into freedom.

1860 - 1865: The Civil War

During the Civil War, she served as a spy, scout, nurse and cook in the US Army. In a mission with Col. James Montgomery, she helped the army rescue more than 700 enslaved people during the Combahee River raid in South Carolina.

Many of those people joined the Union army, the National Park Service says.

1869: Tubman’s second marriage

Tubman married Nelson Davis, a civil war veteran, in 1869 and the two eventually adopted a baby girl named Gertie, according to the Harriet Tubman Historical Society.

1890s: Women’s movement

In the 1890s, Tubman became more involved in the women’s suffrage movement. She spoke at events and worked with Susan B. Anthony, History says.

1913: Tubman’s death

Tubman died on March 10, 1913, in Auburn, New York. It’s the reason the US celebrates her achievements on this day. Before her death, she underwent brain surgery because of the head injuries she sustained early in her life.

Friends and family buried Tubman with military honors at Fort Hill Cemetery in Auburn, the National Park Service says.

She will forever be known as an American hero. So much so that former Treasury Secretary Jack Lew announced a plan to redesign the $20 bill in 2016 and move President Andrew Jackson to the back, making way for Tubman.

But in 2019, Treasury Secretary Steven Mnuchin said that his decision to delay the introduction of a planned $20 bill was technical, not politically motivated.