War is unpredictable. For some reason it seems that things were on the side of the North. In the battle of Chancellorsville, the Union general made an absurd mistake to give up a high ground with every possible military advantage  and go into the thick woods.  But it seems that mistake was the cause of General Stonewall Jackson being accidently shot and killed by his own men due to the darkness and thickness of the woods that made fighting in them incomprehensible. To that loss even General R.E. Lee more or less implied that after that,  the war was almost guaranteed to be lost.. 

Still it is hard to know. There is a verse in Proverbs ,"Woe to the land that a slave becomes its king." [as happened in the USA]. And there is a statement from the sages: "A person who does a favor for one who does not appreciate it is as one who throws a stone at Markulis." [Markulis is an idol whose worship was in the fashion of throwing stone at it.] And in the USA, it is hard to find a black person who is grateful to the USA for freeing them. Most hate the USA, and are determined to bring it down.