From his early days in slavery until the outbreak of the Civil War, Frederick Douglass had been active in the Underground Railroad. The Underground Railroad was Douglass’s longest and most sustained form of activism, foundational to all other aspects of his abolitionist thought. Douglass’s encounter with the Underground Railroad began with his earliest experiences of slave resistance – of secret communication, mobility, and running away. It continued with his own attempts to run away to the North. As a northern abolitionist, Douglass became a leader in the Underground Railroad. He helped hundreds of runaways, unifying slaves’ secret, underground resistance with the public work of antislavery agitation. Underground work proved crucial to the formation of Douglass as a thinker. He learned to read and write underground. Moreover, he developed his literary style and political philosophy – his ideas about women’s rights, internationalism, and direct action – through praxis in the Underground Railroad.