Basic Information
Name: Sam/Dred Scott
Nickname: Great Scott
Born: Sometime in 1795
Died: September 17, 1858
Nationality: American
Hometown: Southampton County, VA
WORK & EDUCATION
Occupation: Slave, hotel porter
Education: None
FAMILY & FRIENDS
Parents: Unknown
Siblings: Dred Scott (the famous one supposedly took his older brother's name when he died)
Spouse: Harriet Robinson
Children: Eliza, Lizzie, and two sons who died in infancy
Friends: Abolitionists, Dr. Calvin Chaffee
Foes: The Supreme Court (especially Chief Justice Roger B. Taney), John Sanford, slavery
Analysis
Given that he became one of the most unintentionally influential people in American history, we know almost nothing about Dred Scott. The year and place of his birth are a mystery. He was born into slavery, although we're unclear where or under what master. He was supposedly named Sam, but changed it when his brother (named Dred) died. (Source)
He definitely had the name after he was sold to Dr. John Emerson, a military doctor. When that happened is also unclear, it was sometime between 1830 and 1833. What is known is that his first masters, the Blow family, remained a part of Scott's life and helped him during and after his trial. (Source)
What's Up, Doc?
Dr. Emerson was apparently a sub-par doctor and not suited to frontier life. A few years after buying Dred Scott, the doctor was sent to Fort Armstrong in Illinois and later Fort Snelling, Wisconsin, which were both non-slave territories according to the Missouri Compromise. (Source)
Before leaving for the forts, Scott met young Harriet Robinson, and they were soon married. She was the slave of another military doctor, but they transferred her ownership to be the same as her husband's.
How nice of them? Um.
When Emerson died in 1846, Scott tried to buy his freedom from the doctor's widow, but she refused. Scott went to the Missouri courts, to argue that their time living in free territories meant that they were now free as well. Little did he know what he was getting himself into.
The Not-So-Supreme Court
Scott filed his case in St. Louis in April 6, 1846 against Irene Emerson, and later John Sanford, the executor of Emerson's will (the extra "d" in Dred Scott v. Sandford was added as a clerical error when the case reached the Supreme Court). The case between 1846 and 1857 has numerous twists and turns, with some judges finding in favor with Scott, and others in favor of Sanford. Each party would appeal, until the case made its way to the Supreme Court in 1856.
For some more detail about the legal course of the trial, look here (starting with the quote "He is entitled to his freedom.") and here.
Throughout the many, many years of trials, the Scotts were helped by abolitionists, especially once the case got to the Supreme Court. They had a strong case—there was precedent for slaves gaining their freedom for the same reason. For example the Moses Bell case of 1844 had given Bell his freedom based on the same principle—and he had only barely moved across state lines. (Source) Scott, like Bell, brought the suits under a specific Missouri statue for people who felt they had been wrongly held in slavery. (Source)
Apparently, this was a common enough problem that laws had been passed.
However, the Supreme Court ruled against Dred Scott in the end. Well, sort of. What they did was decide that they couldn't rule on the case, because—surprise!—Scott wasn't a citizen. Chief Justice Roger Taney, in his court opinion, stated that no Black people could be citizens of the United States.
Less of a surprise, this meant that Scott was not, in fact, free.
Taney took it a step further, unnecessarily declaring that the Missouri Compromise, which was the basis for Dred Scott's claim, was unconstitutional. Apparently, Congress wasn't supposed to decide anything about slavery—the Founding Fathers totally didn't mean that when they wrote the Constitution.
Land of the Free?
The Dred Scott trial had been a huge national story, and caused a justified amount of outrage at the result. Once the trial was over, Irene Emerson and her more charitable new husband Dr. Calvin Chaffee decided maybe they shouldn't continue to own the most famous slave in America.
Chaffee was an abolitionist, and ensured that ownership of the Scotts was immediately transferred back to the Blow family, with the understanding that they would immediately free them. He couldn't do it himself because you had to be a citizen of Missouri to free a slave there. (Source)
After finally getting his freedom, Scott worked as a porter for Barnum's Hotel in St. Louis. Unfortunately, he died of tuberculosis only a year after being freed.
Although much of the detail of Dred Scott's life are shrouded in mystery, his decision to use the legal system to fight for his freedom became one of the catalysts for the Civil War, by widening the divide between the anti-slavery North and the pro-slavery South. Lincoln discusses it at length in the "House Divided" speech.
It's amazing what a little thing like a Supreme Court case will do for your public image.