I want a war between two iron-age cultures, Town A and Town B, based on the "haves" and the "have nots" where they both exist in the same exact climate and geography, however, Town B has been fortunate enough to have formed along the coast of a lake with limnic activity, the other is not. The one town has dropped a long metal pipe down into their lake (the way France put one in Lake Nyos), and the lake provides a steady flow of what they call "the breath of the gods"—concentrated CO$_2$ gas.
(This part is not being asked, it only paints the backstory) For whatever religious reason, at some point someone "got high" off the gas (carbon dioxide intoxication is a syndrome today) from the lake and they began a quest to get more of it. Over time they dropped a pipe, and the gas flowed to the beach. More time passed, plants grew big near the pipe. In the end, they fenced off their crop fields and did everything possible to increase the CO2 concentration around their crops.
Today (in world), Town B has enormous harvests and a bounty of fruits and vegetables from their lakeside fields (which are conveniently downhill from the lake). Town A has routine yields and encounters famines and moderate food production. Town B starts outrageous taxation schemes, demands top prices, and generally aggravates the economies of others who trade with them.
- The CO$_2$ propagates along the ground because it is heavier than air, but eventually will rise up. This is consistent with actual observations at Lake Nyos and other limnic sites.
- Town B has learned about CO$_2$ poisoning and has moderated their exposure to the crop fields, by limiting time, or by shutting off the gas during harvest and pollination season.
- I will say that they have glass and make limited use of it to build at least a partial greenhouse. Nothing at the efficiencies we have today with acrylic and plastics; but an advantage.
The proposed impetus for war
Town B discovered that this "breath of the gods" not only gave them spiritual insight, but blessed their crops with huge and mystical gains. They cherished and worshipped it, and hid it away in secret. They fortified the venting pipes within a temple along the shore of the lake and built a raised floor to allow the magical stuff to flow underneath. Doors along the base of the temple were fitted, so the priests could lift them and close them as needed, and a chimney diverted the gas to the top of the temple when it was not feeding the crops.
In short time, wagons of cabbage heads 2 feet in diameter, cucumber that were larger than a squash, and corn carts which overflowed began arriving in Town A and other neighboring areas. Town A bought up many of these products for seed stock, hoping to duplicate what Town B was doing. They planted their cabbage, corn, cucumber, and onions and barley, but came up with only standard crop yields. A monster-sized broccoli bought by one farmer took top dollar at the fair, but when he carefully rooted a stock, and also cultivated the seeds, only a small broccoli was produced. This put them in dismay, and confusion. They felt tricked.
Town A became angry at this deception, because the principles of agriculture are well known. These crops have been tainted somehow, and magic was suspect. Town A sent an envoy to Town B to try to purchase the secret to these miracle crops, so Town A citizens could benefit as well. The answer from Town B was to lead the envoy into the temple, set them into a small room, and recite a ritual chant. The envoy became dizzy, and started hallucinating meaning into the words. Frightened, the envoy bolted out of the temple proclaiming witchcraft.
Upon returning to Town A, the Lord of the town put a ban on produce from Town B. Promptly, the black market formed from farmers on the outskirts, beyond the immediate sight of the Lord's palace and guard. The Lord then became furious, that his people were still eating these cursed monster vegetables and fruits from Town B, and stealing from tax dollars assessed on local farm produce. Local farmers could no longer raise enough money from their meager crops to provide tax money for the town expansion programs.
Town B produce became legendary throughout the land as far as it could be carried without spoiling. The market for Town B produce took on celebrity status, and it was even filling markets in elixirs, snake oil salesmen, magical and mystical remedies. Anything at all which grew in Town B could be turned into money eventually. All of the scientific community was puzzled at the complete failure to duplicate these results. Throughout the land, farmers competed to find the secret of this amazing bounty, and lords and kings who sampled these miracle crops offered huge prizes for anyone who could discover the secret. But it was of no use at all, no method known to man would ever allow any crop that had grown outside of Town B to have a similar size and yield.
But a bigger insult awaited them yet. The crops were so bountiful and full, that their livestock market was increased by the same proportion. Cattle grew to mythical bulk and stature, horses from Town B were toned and fit like none other. Pork and fowl were fat and prolific in their production. The crops and the land itself were assigned pure magical properties, which for reasons no one could possibly explain, were permanently inked to something Town B was doing.
As the bounty of food flowed through the black market at higher prices, people flocked to the borders of Town B and tried to buy land, gain residency, and even swear fealty. But Town B would not allow foreigners to buy their land, or have their mysterious Breath of The Gods (which has been kept a secret this whole time). Towns which did not boycott the magical produce fell into financial ruin as their meager crops could not compete, and towns which did boycott the produce ran rampant with crime from the black market they created; causing them to spend more tax money on guards, jails, and sheriffs. It became apparent that there was only one single way to get ahead of this crisis. War.
Would this scenario create a food disparity that could precipitate a war?