Why does Harriet Stowe(Uncle Tom's Cabin), position the slaves back to Africa?
Harriet Beecher Stowe was a member of the American Colonization Society which worked to return freed slaves to Africa, in particular to the nation of Liberia, named for liberated slaves. The capital of Liberia, Monrovia, was named for President James Monroe, also a member of the society.
Stowe, as well as other members of the society, were racist to the core. They did not believe that black and white people could or should live together peaceably as equals. To them, slavery itself was an abomination to be abolished; but the former slaves themselves were to be sent "home" as soon as possible. They ignored the obvious fact that slaves at her time had almost all been born in the U.S. Africa was completely foreign to them. If one reads Uncle Tom's Cabin, one sees that Stowe's attitude toward Blacks is condescending at best, and at times borderline contumacious.
At the end of the novel, Stowe has George and Eliza living in Liberia. This was her idea of a "happy ending" to the slavery question.