One of the most interesting developments of political theory in the United States is that which arose out of the controversy over slavery in the years between 1830 and 1860. During the period of the Revolution and the early days of the Republic the general sentiment was unfriendly to slavery. Certain influences were at work, however, that tended to bring the question of slavery into greater and greater prominence. The bitterest attacks on slavery were made by the Abolitionists, but they were not the only or perhaps the typical opponents of the system. The impulse to the anti-slavery crusade was given by the radical Abolitionists, and their doctrines and tendencies may therefore be first considered. The ultra-radical wing of the Abolitionists did not stop at denunciation of slavery and of the United States government for failing to put an end to it.