the 1854 Kansas–Nebraska Act, designed by his great rival, Illinois Senator Stephen A. Douglas. The Act was a radical departure from the previous law of the Missouri Compromise of 1820, which had banned slavery from all new states north of the 36°30′ parallel (except for Missouri). Lincoln suggested that if slavery were allowed to spread it would block free labor from settling in the new states and, as a result, the entire nation would soon become ever more dominated by slave owners. When Lincoln became president, the departure of the Southern members of Congress at the beginning of the Civil War made it finally possible to abolish slavery in the District of Columbia. The District of Columbia Compensated Emancipation Act of 1862 provided partial compensation to slave owners, paid out of federal funds. Lincoln hoped to persuade the border states of Maryland, Delaware, Kentucky, and Missouri to do the same, because that would eliminate their incentive to secede from the Union to join the Confederacy. Their secession might result both in the North losing the Civil War and in the continued existence of slavery. On September 22, 1862, having waited until the North won a significant victory in the battle at Antietam, Lincoln used the power granted to the president under Article II, section 2, of the U.S. Constitution as "Commander in Chief of the Army and Navy" to issue the preliminary Emancipation Proclamation. It provided that, on January 1, 1863, in the states still in rebellion, the enslaved people would be freed. On January 1, 1863, as promised, he issued the final Emancipation Proclamation, which declared "that all persons held as slaves" in "States and parts of States ... in rebellion against the United States" on that day "are, and henceforward shall be free." The proclamation immediately freed on paper millions of the enslaved, but it had little practical effect until the Union Army was present. Week by week, as the army advanced, more slaves were liberated. The last were freed in Texas on a day they called "Juneteenth" (June 19, 1865), which became a federal holiday on June 17, 2021. Although Lincoln stated in the Emancipation Proclamation that he "sincerely believed [it] to be an act of justice," he issued it as a "military necessity," because he believed that the U.S. Constitution would not permit it on any other basis. The Emancipation Proclamation was a war tactic, because