Even prior to the civil war victory some of the northern states had already enacted freedom legislation.  And you can recall how the underground railroad was transporting escaping slaves into some free northern states.  The clergy had also leading the freedom efforts, for a number of years before the Civil War. 

So I'd credit all those leaders and legislators who were pushing in that freedom direction, even before that bloody war.  Quite a lot of commendable details in history which should not be ignored or subdued.  Which is the big flaw of 1619.