His slave revolt would have worked if supplied properly by the North. Except, unlike North Viet Nam and China before that, I don’t think the US Government would have let abolitionist militarily support a slave insurgency in the South. Most people don’t think much beyond John Brown’s failed raid on Harpers Ferry. It failed and failed disastrously. History is settled. John Brown was probably insane and definitely dangerous.
What they don’t realize is that there are historical examples before and after his raid that prove it could have worked.
First, lets agree he actually thought of using the mountainous spine of the Appalachians as a critical passageway (North and South) for his military purpose. It is already established fact that slaves used the mountains to escape North. John Brown envisioned these same mountains as a passageway South for his liberating army of slaves. As evidence, the following map was found in his diary. He envisioned the Appalachians as a conduit to raid plantations.
Swamps were also indicated on his map for purposes of evasion and concealment.
Second, these same mountains were currently used as successful routes North as part of the Underground Railroad or at least the wilderness version of it. If it worked in one direction, it could have worked in the other.
He probably got his idea for a successful insurrection of slaves using the mountains as cover from the island of Haiti. The slaves there led a bloody revolt of their masters using the terrain. Once in control, they turned into viscous Jacobins and slaughtered everybody who was white. Bad idea. No sympathy was gained for their cause by the international community as a result. John Brown’s plan was never to destroy the plantation population but merely free slaves and send them North to Canada along what he called the “Great Black Way.”
Again, my point here is only to argue the merits of his raid on Harpers Ferry. First. He would “liberate” the federal armory, escape with the weapons into the surrounding mountains, then lead an ever growing army of slaves South to free even more. Kinda like Spartacus without the sandals and togas. History tells us that the military tactic of using mountainous terrain worked in Haiti and then again in Viet Nam.
The communists effectively used mountainous terrain and geographic boundaries to move deep into South Viet Nam. While their inferior military technology could never sustain open combat with the United States superpower, it can’t be debated that the wilderness of Indochina benefited their cause. Yes, we were limited to a great extent by politics to properly fight our war against the agression from the north vietnamese but I have to wonder which side of politics John Brown’s slave army would have fallen to. Would he have received support from the Federal government or crushing suppression? Or, maybe just ambivalence? The later cost us victory against the communist invasion of South Viet Nam. Would an ambivalent Federal response have allowed his slave revolt to succeed? Was the only flaw in his plan a terrible miscalculation of federal support for the freedom of slaves? While the civil war cost enormous death, destruction and suffering, it ultimately freed the slaves but only after he was hanged.
My book ponders the question why would the same US government execute John Brown for a cause it would within a year pursue relentlessly.
Just to close the loop, in case you were wondering, my fascination with the Appalachian Trail is directly linked to this history. Yes, it is nice to hike and enjoy the solitude of the wilderness. My mind, however, always populates this footpath with historical phantoms. I would not call them ghosts but images etched into the landscape. Not sure what I am seeing out there exactly. It is certainly more than simple flora and fauna. Whatever I see in the woods, it plays like a grainy old film. Scratched and flickering, the images look surreal. You could say that the past haunts me. Events happened but not the way history tells us. Through my lens, I see how it might have been or actually was. The facts don’t lie. Yet, they persist even though not reported. We must correct the record. It is a thankless task but someone has to do it. 
It is a thru hike I must do if I am ever to finish my trilogy. I am cursed to complete it. It will be a hike of the damned.