At the time he wrote these words Lincoln had already decided on a policy of military emancipation in the rebel States. He doubtless wrote them with an eye of the possible effects of that policy. He wished the Northern Democrats and the Unionists of Border States to understand that his action was based upon considerations of military expediency and in no way upon his personal disapproval of Slavery, of which at the same time he made no recantation. On the military ground he had a strong case. If, as the South maintained, the slave was simply a piece of property, then the slave of a rebel was a piece of enemy property--and enemy property used or usable for purposes of war. To confiscate enemy property which may be of military use was a practice as old as war itself. The same principle which justified the North in destroying a Southern cotton crop or tearing up the Southern railways justified the emancipation of Negroes within the bounds of the Southern Confederacy. In consonance with this principle Lincoln issued on September 22nd a proclamation declaring slaves free as from January 1, 1863, in such districts as the President should on that date specify as being in rebellion against the Federal Government. Thus a chance was deliberately left open for any State, or part of a State, to save its slaves by submission. At the same time Lincoln renewed the strenuous efforts which he had already made more than once to induce the Slave States which remained in the Union to consent voluntarily to some scheme of gradual and compensated emancipation.