I've read the argument that couching the war as a test of whether government by the people could long endure is nonsense. There were, and would be, others. The same author (Adams) says Lincoln asked 'What about my tariffs?" - that the north had enjoyed most of the tariffs since the 1820 compromise, including those collected at southern ports, so the south was going to be a 'free port' nation, to the destruction of the northern economy. Wow, huh?