When did President Lincoln sign and issue this document and at what stage of the Civil War? Did the document have any real impact?

Although the Emancipation Proclamation didn't actually free any slaves, it did have a huge impact on the war effort:Southern slaves knew that real freedom, as opposed to the ideal of freedom, awaited them in the Union, giving them greater cause to flee north or to undermine Confederate strategies. The Emancipation Proclamation also guaranteed that African Americans - both runaway southern slaves and northern freemen - would be allowed to join the Union army and navy and fight against the Confederacy. Almost 200,000 African Americans, mostly former slaves, contributed to the Union war effort; around 37,000 of those gave their lives for it. The Emancipation Proclamation redefined the purpose of the war. What had begun as a test of whether a state could withdraw from the Union became an ethical battle over the future of slavery in the United States. President Abraham Lincoln issued the Emancipation Proclamation on January 1, 1863,