>Lincoln had to use the Emancipation Proclamation as part of his strategy.
I had to help my daughter answer a question about the Emancipation Proclamation for a second grade assignment earlier this year, around President's Day. The phrase "did not free a single slave" is commonplace in the literature about it now. This is from Encyclopedia Britannica. It's the beginning of an intro to the text itself:
>In the popular mind the Emancipation Proclamation transformed the
>Civil War from a struggle to preserve the Union into a crusade for
>human freedom. But at the time of its issuance, its actual
>provisions had already largely been enacted into law by Congress,
>which had provided for the freeing of slaves of owners hostile to
>the Union, the prohibition of slavery in the District of Columbia
>and the territories, and the freeing of slave-soldiers. The
>Emancipation Proclamation actually did not free a single slave,
>since the regions in which it authorized emancipation were under
>Confederate control; in the border states where emancipation might
>have been effected, it was not authorized. It did, however,
>tremendously boost Union morale, breed disaffection in the South,
>and bolster support for the Union cause in Europe. The real
>significance of the document lay in the political factors that
>brought it to fruition and in the delicate political balance it
>preserved. [....]
http://www.britannica.com/presidents/article-9116929