Yes. During the Revolution Lord Dunmore the Royal Governor of Virginia issued a proclamation promising freedom to any slave who ran away and served in the British forces. They were formed into Lord Dunmore's Ethiopian Regiment and gave undistinguished service being used mostly as labor to prevent Southern loyalists from worrying too much about their own slaves being incited to rebel and the unit was disbanded after a year or so but the British continued using runaways as labor with the promise of freedom.

During the war 10s of thousands of slaves escaped and several thousand were resettled in Canada after the war who had sought refuge in New York.

Yes actually, they did. Dunmore's Proclamation in a way does exactly that. Earl of Dunmore promised emancipation if black slaves left their Patriot masters and joined the Loyalists against the rising "rebellion." He formed them into the "Ethiopian regiment" after receiving several hundred runaway slaves. His attempts to regain control did not last long as he was forced to flee after losing at the Battle of Great Bridge.

That being said, he only technically only offered the emanicpation to slaves of Patriots but that did not stop slaves from running away from Loyalists either.

There was also a conspiracy in North Carolina that Governor Josiah Martin was planning a slave rebellion against Patriot owners by providing them with arms and proclaiming freedom to all that joined the Loyalists. This was in the summer of 1775 and Lexington and Concord had not been too long ago at this point. tensions were high and the danger of slave rebellion was very real to many Patriots. The Committee of Safety in Pitt County did find a slave that planned an insurrection and forty other slaves were questioned. Martin denied that he had such plans, but did admit it would have been useful to quell the current Patriot rebellion.

For the less educated (and misinformed), what was behind the Emancipation Proclamation. Can you explain the context for this as an act of war? (I agree with you. I'd just like for you to explain it if you have the opportunity.)