For some years before the war began it was a trite saying among some politicians that "A state half slave and half free cannot exist." All must become slave or all free, or the state will go down.

I took no part myself in any such view of the case at the time, but since the war is over, reviewing the whole question, I have come to the conclusion that the saying is quite true.
Slavery was an institution that required unusual guarantees for its security wherever it existed; and in a country like ours where the larger portion of it was free territory inhabited by an intelligent and well-to-do population, the people would naturally have but little sympathy with demands upon them for its protection.

Hence the people of the South were dependent upon keeping control of the general government to secure the perpetuation of their favorite institution.

They were enabled to maintain this control long after the States where slavery existed had ceased to have the controlling power, through the assistance they received from odd men here and there throughout the Northern States.

They saw their power waning, and this led them to encroach upon the prerogatives and independence of the Northern States by enacting such laws as the Fugitive Slave Law.