So, let’s say in a post apocalyptic world, their are two fighting forces. One army is equipped with Civil War-esque weaponry (cannons, rifles, horses) called the USCA and the other army is fighting with late-1960s American Vietnam weaponry (Automatic Guns, Helicopters, motorized transports) called the Bunker Force.

The USCA outnumbers the Bunker Force at a scale of 17:1, as the Bunker only has 1000 or so personnel. My question is, since their is a large gap in technological advancement, what tactics would be most effective for the USCA to win the battle?

Fight dirty & avoid actually fighting

If you stick to conventional warfare the civil war equipped faction will lose every time, a tank is pretty much immune even to the strongest cannon that the civil war area faction owns (and everything else they have), this means that a single tank can just steamroll over them.

The same goes for helicopters, there is noting in the civil war area armory that could even hope to hit it so it can just stay high up and rain down hell on the civil war faction until they all die... I imagine for the pilot it will be noting more dangerous then a target practice is.

Even if you move to a 1000 strong modern infantry only the chances are still brim for the civil war area equipped faction as the modern infantry man is easily equipped with more firepower then an entire legion of past days, they can spot them from further away (scopes, night vision, thermal googles), hide better (modern camouflage), fire faster (a pair of machine guns can fire more rounds per minute then the entire 17000 civil war "army" faction can combined), are better armored (modern ceramic plates can stop a musket ball), communicate easier (radios), move faster (cars are fast) & their bullets travel faster & hit harder.

But if we go to fighting dirty then there is a chance, maybe the modern faction have a traitor that poisoned all their foodwater supply? (poison existed since the dawn of history), maybe they do to them what they did to native Americans (only this time not by accident) and give them a "surrender" token that includes highly infectious disease?

Who is fighting for what?

Those thousand motorized/airmobile troops -- call it a short infantry battalion and a few trucks, APCs, and helicopters -- can defeat any concentration of civil-war-era troops. They cannot maintain many roadblocks, firebases, or search-and-destroy patrols.

• If the Bunkerites operate in platoon strength or more, try to fade away. Go into forests or broken country, split the unit into smaller teams, and so on.


• If the Bunkerites send out squads or sections, try to concentrate an USCA company or more and attack. Sure, the USCA will take casualties, but if their troops are halfway disciplined and trained, they will prevail.

Once the Bunkerites realize this, they will be left with roughly ten units that can move halfway safely, and even such a platoon would be vulnerable to a well-executed battalion-size ambush.

And don't forget that the Bunkerites need to defend their airbase, too. That could take a company or so.

Does the USCA have troops who would be willing to die to "take one with them?" If just one or two percent of them think that way, the Bunkerites cannot really move except by air ...

Without knowing too much detail about either side, it's difficult to give more than broad outlines. It would depend on the training of either side, the terrain, the logistics of how each side is supplied, etc.

One example that could be relevant is the tactics of the Finnish in the Soviet-Finnish winter war. Provided the environment allows USCA fighters to quickly vanish after disengaging (forests, jungles, urban environments etc), focusing on attrition of their supplies (as opposed to manpower) could work.

By constantly harassing smaller outposts, small groups of USCA could continuously attack isolated pockets with sporadic fire with the intention of goading them in to using up much needed ammunition, then falling back without taking any real casualties.

Softer targets, like supply lines, could be prioritized instead of engaging the Bunker Force in any major battle. Using the environment, like felling trees and blocking roads in isolated areas along the supply lines, then ambushing supply convoys would allow them to inflict casualties and more importantly disrupt the logistics of Bunker Force.
BF would have to devote considerable amounts of resources to protecting their supply lines once it's clear that the USCA is focusing their attacks on them. Over time they could bleed the supply lines out and wear down the BF before attempting any major engagements.

This does kind of rely on the BF being the aggressors here, and trying to take and hold large territories from the USCA (in which case they would be overstretched with vunerable supply lines). If it's the USCA sieging a BF stronghold (like a port or bunker) or facing them in direct combat, then there is no real way the USCA can actually attack and hope to win; modern automatic weapons would be incredibly effective at cutting down infantry attempting to close in with muskets, not to mention the artillery and air support of BF.

I would start by defining the tooth-to-tail ratio of the technologically superior force. In modern militaries roughly 1/3 are combat troops (“teeth”) and 2/3 are support troops (“tail”). This ratio varies, obviously, but these ratios are reasonable ballpark figures.

So, if 300 of the 1,000 are fighting troops that also infers maybe 12-24 combat aircraft (you can google and research the sizes of squadrons and air wings if you want more precise numbers). Since this is Vietnam-era tech, you’re probably looking at a dozen or so Hueys and a dozen or so Cobras. Just a guess, but that probably means less than 50 tanks. Maybe closer to 25.

The primitive force is clearly outgunned, but we now have idea what the primitive force is up against. A few lucky breaks against the supply chain, or even against the combat forces, will degrade the techno giant below the level needed to sustain combat operations.

So, what does the primitive force do? It should avoid direct frontal assaults at all cost. Assuming similar tooth/tail ratios, a human wave of 6,000 could charge, but the casualties would be horrible. Instead, they need to rely on maneuver and surprise, mostly using hit-and-run tactics.

First priority will be to hit supply lines and supply depots. Without fuel, all those fancy machines stop moving.

Second priority is to stop the enemy air power. Shelling them on the ground with civil war cannons would be the most effective, but it will be difficult to get horse-drawn artillery in range unseen. Guerrilla attacks on forward operating bases to damage the choppers with dynamite is probably more realistic.

Once airborne, the defenders have few weapons that can damage a chopper, barring a lucky rifle shot. But, the defenders have a few options: creating flak by detonating time fuzed artillery shells. You can google and research their usage during the civil war. Also, releasing balloons just ahead of choppers in an attempt to entangle ropes in the rotors. This is probably only effective against low altitude targets taking off and landing. And probably only works once, then the pilots will climb/descend directly over their base. Again, you can google and research recon balloon usage in the civil war to get more details about the capabilities. Both of these tactics will require a fair bit of luck and the element of surprise in order to be effective.

Assuming you can whittle away at the air power, the ground forces have a number of hit-and-run and ambush options available. They won’t be able to penetrate modern armored vehicles, but dynamite will blow the track off of a tank. Blocking the main gun barrel will still cause it to explode. Dropping dynamite into an open hatch will still kill all the occupants. Dynamite with a plunger detonator can still be an effective roadside IED. And shelling infantry with canon balls—if you get a lucky break and manage to get in range undetected—can inflict a lot of damage. Hiding artillery around a choke point like a mountain pass could get an opportunity to ambush a convoy, damaging the unarmored vehicles and accompanying infantry. All of these things require surprise and mobility by the defenders, and generally getting very close to small groups of attackers.

Most likely, although your defenders may win a battle here and there, they are not going to win this outright. However, looking at examples ranging from the American Revolution up-to-and-including British, Soviet, and US excursions into Afghanistan, your defenders can create an long-term, bloody slog that eventually becomes too expensive for the attackers to sustain. In an ideal case, the primitive force may be able to bloody the techno giant just enough to distract it, letting a suicide squad infiltrate some key resource/support station and blow it up, bringing the techo giant to it’s knees.

Note: the larger you make the techno giant, the less likely these tactics will work.

Note2: the primitive forces will have to use terrain to their advantage. In the open plains of the US midwest, the primitive forces have no cover and little chance. Nestled in the Rocky Mountains, though, they may be able to use the terrain to their advantage. So consider your setting carefully.