Thank you Andy, I'm much obliged. One more question and then I'll not bother you further. Do you think the Emancipation Proclamation, issued at the time it was, was primarily more of 'saving the Union' than a definite intention to announce his determination to free the slaves?
For Lincoln personally, I believe it was a happy confluence of both his war aims (to defeat the rebellion) and his long-standing desire to end the practice of chattel bondage. He probably guessed, correctly, that once emancipation was made official policy of the U.S. war effort, there was no going back, no way to get that genie back in the proverbial bottle.
It also helped to slam the door on possible active intervention by the UK on the side of the Confederacy, since much of British foreign policy over the previous decades had been devoted to curtailing the international slave trade and dealing with emancipation in its own colonies in the Americas. It would have been exceedingly difficult for Palmerston's government formally to ally itself with the Confederacy in any case, but especially so after the EP.
Lincoln had been pushed by officers like Fremont in the West and Butler at Fortress Monroe recognize that slave labor was a key competent of the Confederate war effort, just as much as southern railroads and foundries and mills were. And since the Confederates themselves viewed enslaved persons as another form of property, that provided sufficient justification for taking formal and official action to remove those resources from the hands of rebellion. but Lincoln well knew that the EP was only as effective as the Union armies could retake ground in the rebellious states, and could only be enforced by Federal occupation.
Lincoln also understood that the EP was a wartime exigency that would almost certainly not stand legal scrutiny once the war was over, and the Confederate states (presumably) were returned to Union. That's why, at the end of the war, he pushed hard to pass the Thirteenth Amendment that settled the question fundamentally.
In many respects, I think we Americans hail the Emancipation Proclamation more than we should, because it was the Thirteenth Amendment that actually accomplished the deed.