Lincoln's strategy required the forced labor (and for some, subsequent deaths) of tens of thousands of people. The irony of conscription wasn't lost on Americans at the time either, and the military drafts were extremely unpopular on both sides.
Lincoln's strategy itself was "required* because slave-owners and slave-owning states would not give up their slaves without a fight. Blame them, not Lincoln.
Lincoln himself was well aware of the costs that would be imposed by war, but chose this course of action due to the absurdly perverse nature of slavery.
I don't doubt that Lincoln personally resolved his internal ethical dilemmas, but I do doubt that this would be any consolation to me if I were forced to fight in an army.
