The Thirteenth Amendment to the U.S. Constitution legally ended slavery in the United States. It was passed by Congress and ratified by the required three-fourths of the states in 1865. President Abraham Lincoln had issued the Emancipation Proclamation in 1862, declaring slaves in areas in rebellion against the government to be freed by executive decree. Afterward, Lincoln and many of his fellow Republicans had believed that more permanent legislation in the form of a constitutional amendment prohibiting slavery would be needed to ensure that the Emancipation Proclamation could not be subsequently ruled either unconstitutional or a temporary war measure. The Thirteenth Amendment was the first constitutional amendment to be adopted in over sixty years, and it initiated a series of subsequent amendments, including the Fourteenth and Fifteenth, with which it is often associated. Those two Reconstruction-era amendments guaranteed citizenship and voting rights to African Americans, and along with the Thirteenth Amendment they represented a crucial step in the broadening of the American legal definitions and conceptions of freedom and equality.