The north's original plan was to make the CSA rejoin the Union.This is why they were on the offensive.
The south just wanted independence from the Union.After the attack on Ft. Sumter they went on the defensive.
The major turning points were Antietam because after that the Emancipation price was issued and Gettysburg because it really hurt the south's army and forced them to retreat deeper south.
The north had several advantages. They had more troops,Better weapons,More weapons,The British and French,And Abraham Lincoln as the country's leader.
Hope that helps.
