Banks’s biographer Hollandsworth says that Banks was a moderate who won support among those who thought Brown was too extreme.
BJK: "Can anyone source and verify the claim that Banks responded to Brown's hanging by raising six regiments of Massachusetts state militia?"
Sherman Logan: "Remarkably difficult to find anything about what Banks did as governor.
He was known for reorganizing the militia, but I can find nothing about this having any relation at all to JB."
x: "Banks’s biographer Hollandsworth says that Banks was a moderate who won support among those who thought Brown was too extreme."
On your mention of it, I bought Hollandsworth's book.
It describes Republican Banks in 1859 as a political moderate, a "trimmer" who tried to please all sides, and usually succeeded politically.
But Banks' opposition to the radical abolitionists who supported John Brown cost Banks a united Massachusetts delegation at the 1860 Republican convention.
That in turn lost Banks his opportunity to be on the Republican national ticket as President or Vice-President.
Hollandsworth mentions nothing specific about Governor Banks' relation to the Massachusetts militia, or whether in 1859 Massachusetts' was different from other state militias.
Yes, as a state legislator in 1853 Banks did speak in favor of a militia at his states' constitutional convention, and as Governor in 1859 Banks did watch a fine parade of his state militia.
But there's no evidence any of that had to do with John Brown, or some notion of being ready to go, in lentulusgracchus' words: "to Virginia to put down the South."
Finally, we might note that a Civil War regiment started with ten companies of 100 men each, so six regiments would be about 6,000 soldiers.
In November 1860, more than a month before declaring secession, South Carolina's legislature authorized raising a 10,000 man army.
On March 6, 1861 the Confederate Congress authorized a 100,000 man army, and on May 4, 1861 authorized another 500,000.
Eventually the Confederacy fielded 1,000,000 soldiers and the Union over 2,000,000.
So Banks' six regiments in 1859 -- even if that is the right number -- were hardly adequate to even think about "going to Virginia to put down the South"