The author pointed out that northerners (and most historians since) have misinterpreted southern "unionism."
Southerners obviously fit on a spectrum, with one end favoring secession immediately, and the other end opposing it under any circumstances. The "unionists" Abe and historians have talked about so much were generally fence-sitters, not true unionists. They wanted to put off a decision in hope things would work themselves out, or wait to secede until Lincoln had committed some "overt act" that in their eyes would justify secession.
But unionists were nearly unanimous in opposition to what they called "coercion," which of course meant any attempt to actually enforce the laws of the US in the seceded states."Coercion" in most of their eyes would constitute an "overt act" of oppression.
There were true Unionists in the South, but mostly in the mountains. There were few elsewhere. In Mr. McPherson's opinion, which I think he supports very well, secession was very popular in the South, as shown by those states where a referendum was taken. Opposition was regional, not general.
The fire-eaters successfully precipitated the crisis that led to secession, but they did not intimidate their fellow citizens into secession. The population of Upper South states voluntarily walked straight into the wood chipper.
And you are of course quite right about mood, not move. :)
Lankford's book shows there was a good deal more intimidation of what I'll call "weak Unionists" in, for example Virginia, than you might suppose.
Strong Unionists in mountains of western Maryland, western Virginia, eastern Tennessee, western North Carolina, plus those in most of Kentucky and Missouri all resisted secessionists, so that proves it could be done, but only under special conditions.
Secessionists did not need a majority to take control, but the did need some minimum level of minority to successfully intimidate their weak Unionist neighbors.