The executive order abolishing slavery in the “rebel” (Confederate) states of the USA. The Proclamation, issued by President Lincoln as commander-in-chief of the US Armed Forces, was partly a measure designed to win international support for the Union cause. It was of doubtful constitutional validity. Lincoln had issued a preliminary proclamation on 22 September 1862 advising that all slaves would be legally free as from 1 January 1863. This was now confirmed, to be enforced by military authority without compensation. After the war the US Congress passed (1865) the Thirteenth Amendment to the Constitution, abolishing slavery throughout the USA and thus confirming the constitutionality of the President’s action.