The Fugitive Slave Act was a law passed in 1850 as part of the Compromise of 1850. It required that escaped slaves, who had fled to free states, be returned to their owners in the South. This law made it illegal for anyone to assist runaway slaves and imposed heavy penalties on those who did. The act intensified the conflict between the North and South, as many Northerners opposed the law and refused to comply. It also led to increased activism in the abolitionist movement, with figures like Frederick Douglass and Harriet Tubman working to help enslaved people escape to freedom.