Lincoln issued the first Emancipation Proclamation on September 22, 1862, 18 months after the war started. The US had just defeated Lee's attempted invasion at Antietam and the blockade was in full swing. In the west, New Orleans had fallen, Grant had already occupied Memphis, had troops in Mississippi and was about to begin the Vicksburg campaign. Now, in what sense were they losing?
Lincoln was running out of Irishmen to send to the slaughter so he emancipated a new batch of fresh meat.