When the Fugitive Slave Law of 1850 was passed by Congress, the flight to freedom for runaway slaves became even more dangerous. Even the free cities of Boston and Philadelphia were no longer safe, and abolitionists who despised slavery had to turn in fugitives. But the Underground Railroad, a secret and loosely organized network of people and safe houses that led slaves to freedom, only grew stronger. Since the late 1700s, blacks and whites had banded together to aid runaways like Maryland slave Frederick Douglass, who disguised himself as a sailor to board a train to New York. Virginia slave Henry Brown packed himself in a box to get to Philadelphia. The minister John Rankin, who hung a lantern to guide runaways to his house by the Ohio River, endured beatings for speaking against slavery. Quaker storeowner Thomas Garrett was put on trial for helping fugitives in Delaware. Meanwhile, the nation marched on toward civil war. At its height, between 1810 and 1850, these secret routes and safe houses were used by an estimated 30,000 people escaping enslavement. In The Underground Railroad: The Journey to Freedom, read how this secret system worked in the days leading up to the Civil War and the pivotal role it played in the abolitionist movement.