The Emancipation Proclamation was an unconstitutional (as it both violated the 5th and 10th Amendments and was not something the President had the power to issue) publicity stunt.It only applied to slaves in what was at the time an effectivelyforeign country where he lacked the power to enforce it.
Legally, it had as much force as if the US declared that the subjects of Great Britain could no longer drink tea.
Note that it did not free the slaves in Delaware, Maryland, Kentucky, Missouri. the area know known as West Virginia, the Nebraska Territory and in the Indian Territory (Oklahoma).
Note also that an April 16, 1862, President Lincoln signed the The District of Columbia Emancipation Act, which quite legally and properly freed the slaves held in the DIstrict of Columbia.
Side note: Aguably, runaway slaves resident in DC may still have been subject to the Fugative Slave Acts due to the wording of The District of Columbia Emancipation Act.
I am merely commenting on the legal staus of the Emancipation Proclamation, not supporting either slavery of the seccesion of the CSA.