RE THE SECOND AMERICAN CIVIL WAR

"White colonists interpreted as treachery the decision of the Governor of Virginia, Lord Dunmore, in November 1775, to offer emancipation to slaves who rallied to the British cause." Clark

And so it was.  " Lincoln's Treachery " against the descendants of his own electorate, his own Northern white constituency, under our system, as distinct from the British system.

His was a sectional party, our first, and his a sectional, though unionist, mandate.

The big difference re treachery: the British had compensated British slave owners, and had done so not as a tactic in military manoeuvres.

Lord Dunmore's offer of emancipation to Virginia negro slave was "... not to help the black man...", (cf DK excerpt) but to help the white Northern loyalists, and his own white British troops, against white Northern rebels, 

'Even in the northern states where black citizens theoretically enjoyed equal rights, he reported, they were too afraid to assert them.  Those states that had abolished slavery had done so not to help the black man, but to help the white, both by leaving free labor without the competition of slaves and by eliminating the corrupting influence of owning slaves upon the whites.' DK, re Tocqueville, 2016