By 1862 most northern leaders realized that the mainstay of Southern secession, slavery, had to be attacked head-on. All the border states rejected President Lincoln's proposal for compensated emancipation. However, by 1865 all had begun the abolition of slavery, except Kentucky and Delaware. The Emancipation Proclamation was an executive order issued by Lincoln on 1 January 1863. In a single stroke, it changed the legal status, as recognized by the U.S. government, of 3 million slaves in designated areas of the Confederacy from "slave" to "free." It had the practical effect that as soon as a slave escaped the control of the Confederate government, by running away or through advances of Federal troops, the slave became legally and actually free. Plantation owners, realizing that emancipation would destroy their economic system, sometimes moved their slaves as far as possible out of reach of the Union Army. By June 1865, the Union Army controlled all of the Confederacy and liberated all of the designated slaves. The owners were never compensated. About 186,000 free blacks and newly freed slaves fought for the Union in the Army and Navy, thereby validating their claims to full citizenship.