Lincoln's best hand was the race card.
"But for your race among us there could not be war, although many men engaged on either side do not care for you one way or the other....
You may believe you can live in Washington or elsewhere in the United States the remainder of your life, perhaps more so than in any foreign country, and hence you have come to the conclusion that you have nothing to do with the idea of going to a foreign country. This is (I speak in no unkind sense) an extremely selfish view of the case."
(Abraham Lincoln v. 5, pp. 372-5. Address on Colonization to a Deputation of Negroes, Aug. 14, 1862)
The race card was first played at the Constitutional Convention.
It is true that President Lincoln said in 1864 that without the aid of the blacks, the war would have to be given up in three weeks.
Walt