what was the significance of Uncle Toms Cabin for the antebellum U.S.?

They gained insight into the feelings and perspectives of their slaves. Uncle Tom's Cabin's was the most popular anti-slavery novel and it was internationally read. It caused those in the North to oppose the slavery in the North even more. However, southerners at the time claimed that Harriet Beecher Stowe, the author, had dramatized the experiences of slaves. Uncle Tom's Cabin had somewhat inspired the Civil War and the Emancipation Proclamation. Which greatly impacted antebellum U.S. Supposedly, Abraham Lincoln greeted Harriet Beecher Stowe in 1862 by saying "So you're the little woman who wrote the book that started this great war."

It brought home to many Northerners for the first time the real human condition of slaves in the South at the time,and thus vastly increased anti slavery sentiments amongst ordinary Northerners.

It highlighted the plight of slaves to a vast northern population for whom slaves were out of sight, out of mind. The abolition movement certainly took a lot of fuel from the book.