Lincoln supported excluding slavery from territories with the failed Wilmot Proviso in the 1840s. His 1850s activism was in reaction to the 1854 Kansas–Nebraska Act designed by his great rival, Illinois Senator Stephen A. Douglas. Lincoln saw the new Act as a great evil that was only brought into being through serious and continued violence on the ground. The Act was a radical departure from the previous law of the Missouri Compromise of 1820, which had strictly banned slavery from all new states north of the 36°30′ parallel (except for Missouri).