Lincoln didn't care about freeing black slaves. This is why his Emancipation Proclamation only freed slaves in the South. This is why the Underground Railroad ended in Canada and not Pennsylvania. Lincoln was a high-tariff President, proven by his own words and especially the Morrill Bill. This is why he only proposed freeing any slaves after the Union had lost several key battles in the war. In newspapers of the day, Lincoln's move to free slaves was knows as his "last card" to save his reelection. It was mostly about profit and power, as with most things.