There were many people in the North at that time who were helping runaway slaves to escape from their masters, and in certain parts of the country there were stations of what was called the "Underground Railroad." Negroes fleeing from the tyranny of Southern owners were helped along from one station to another, until they were finally safe across the Canadian border. The law of the country said that negro slaves were like any other form of property, and that it was the duty of citizens to return runaways to their masters. There were also scattered through the border states a number of men whose business it was to catch fugitive slaves and take them back south. These men were usually of a brutal type, and the poor refugee who fell into their clutches was made to suffer for his attempt at escape. Story after story of the sufferings of slaves came to John Brown's ears, and he felt that it was his duty to throw himself into the work of the Underground Railroad, and help as many slaves as possible to cross into Canada. This work was not enough for him, however; he wanted to strike some blow at the slave-owners themselves. The Alleghany Mountain range was one of the main roads for fugitives, for there men could hide in the thick forests of the mountainside, and could make some show of defense when the slave-catchers and bloodhounds came in pursuit. John Brown knew this country well. He traveled through the North, talking with other men who felt as he did, and trying to work out a plan which should force the country to decide this question of negro slavery. At last he decided to make a raid into Southern territory, and free slaves for himself. In the heart of the Alleghanies, and almost midway between Maine and Florida, is a great natural gateway in the mountains. Here the Potomac and the Shenandoah Rivers meet, and seem to force their way through the natural barrier. This pass is Harper's Ferry, and in 1859 it was the seat of a United States arsenal. To the south was a country filled with slaves, who looked to Harper's Ferry as the highroad to freedom. Not far from the arsenal rose the Blue Ridge Mountains, the heights of which commanded the pass. It was John Brown's plan to lead men from the Maryland side of the Potomac River to attack the arsenal, and when it was captured to carry arms and ammunition across the Shenandoah to Loudoun Heights in the Blue Ridge, and hide there. From here his band could make raids to the south, freeing slaves, and shielding them from their masters, while using the mountains for a shelter.