I believe this is pretty accurate quote by Lincoln:"If I could save the union and not free the slaves, I would do it, and if I could save the Union by freeing all the slaves, I would do that as well." I do think, however, that the breaking up of the Union, however had more of a punch to it in the mind's of American's than the loss of Federal taxes that the writer alludes to. Lincoln knew he was not an abolitionist, and felt the South had no need to secede, but ultimately completely underestimated the South's resolve. And after Bull Run - which opened many an eye - neither side would back down.
Today a tyrant reigns and the aware know it. Soon the blood shed on battlefields from Lexington Green to Omaha Beach to Afganistan and Iraq will cal