On March 4, 1861, Abraham Lincoln addressed his fellow citizens, as was the custom of presidents taking the oath of office. His main purpose was to allay the anxieties of the southern states that their property, peace, and personal security were endangered because a Republican administration was taking office. Thus, Lincoln reiterated his promise not to interfere with the institution of slavery. Indeed, he affirmed the rights of states to order and determine their own institutions. To do otherwise, he noted, would violate the U.S. Constitution. Furthermore, he vowed to enforce the federal Fugitive Slave Act, which stipulated that slaves escaping from southern masters be returned to their owners. At the same time, Lincoln argued that the U.S. Constitution was “perpetual,” which is to say indissoluble. In effect, he was denying such states as South Carolina the right to secede. The Constitution could be amended, but the Union could not be broken. Thus he tempered his message of reconciliation with the admonition that under no circumstances would the federal government under his administration tolerate secession.