How did Uncle Tom's Cabin relate to the civil war?

The novel of Uncle Tom's Cabin was written a full ten years before the US Civil War began. In the 19th century with slow communications, ten years is a very long time. It's impact on the war was minimal to none. Also, Harriet Beecher Stowe the abolitionist blamed the North and the South for the institution of slavery. The book sold well but it was a novel, not a documentary. Slavery was an evil but Uncle Tom's Cabin did not make 300,000 Northern soldiers lose their lives.