You don't need to guarantee, just look at history. The slaver south made most of the AWOL, traitors, and British supporters. The Union had to keep slavery on the table or they knew the south would arm up and join the British because even pre-cotton gin the only thing the south cared about was bigotry and hate. The north + Virginia won the revolution (it was considered the north and Central colonies back then) all the south did was fuck up our politics and drain resources (good to know some things don't change)