THE WAR OF 1812 AMERICA STOOGES FOR NAPOLEON

See Schroeder's account starting at p 435. Wonderful stuff. 'A rigid foolish American policy'...'Drift'...

Answered by New England Secession threat.......those rascals! 

No one would have stopped them, New England, on purely constitutional grounds, back then.

The Hartford Convention.

Professor Kaiser makes the case, in a sentence, that the Civil War was fought over the concept of the union versus states' rights, not slavery or not slavery, if I understand his point.

In my judgment, that was not the reason, but the war was caused rather by a sectional and party divisional dispute only over slavery or not slavery. 

See my prior post touching on this topic: SOMEONE CAN CORRECT ME IF I AM WRONG

Lincoln's constitutional union argument had long been lost, had been nugatory really since the beginning, in 1776, but had not been militarily acted against, as far as I am aware, until 1860.