For context, take any generic medieval setting and don't change anything leading up to how society got to that point. However, one day, every tree in the country disappears. Eventually, the wood in the weapons they already have has to rot or break, so they inevitably run out.

Would polearms made entirely of metal be too heavy to be viable? How would they adapt without the use of things like siege towers or bows? Other implications of a world without wood are appreciated but warfare is what I'd like to focus on.

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    $\begingroup$ do they have coal? or coal also gone too? is this specifically mean for generic medieval europe or "medieval age" ? regarding wooden shaft, most medieval india use metal shaft for their weapons, so i dont see a problem, though it maybe unwieldy for pike, but i am not sure myself. and others already mention composite bow. and dirt wall exist too and depend on the technology knowledge they may can make roman concrete. $\endgroup$
    – Li Jun
    Commented Jun 29, 2020 at 17:21
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    $\begingroup$ I wonder at the change of world climate and air composition when both the temperate and rain forests all vanish $\endgroup$
    – CGCampbell
    Commented Jun 29, 2020 at 21:01
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    $\begingroup$ OP, I think it might be helpful to narrow down your time and place a bit, at least the time frame. The difference between Viking-era (wood-handled axes,and wooden shields, boats, etc) and say, the time of the French musketeers (epees and early firearms (the swords wouldn't be affected much, but the muskets and rifles would)). $\endgroup$
    – CGCampbell
    Commented Jun 29, 2020 at 23:22
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    $\begingroup$ Even if all trees are gone, what other types of bushes and small plants remain? $\endgroup$
    – user4574
    Commented Jun 30, 2020 at 1:20
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    $\begingroup$ Without wood, the blacksmiths wouldn't be able to craft iron, and soon the swords would all be gone, and they'd be reduced to hitting each other with rocks. $\endgroup$
    – NomadMaker
    Commented Jun 30, 2020 at 5:02

7 Answers 7

  • Harder to cook in places without alternatives like peat or oil. No wagons or boats to transport fuels economically. Fuel becomes expensive (too much for some folks), particularly off-season. Malnutrition and seasonal starvation reduce the population.
  • Hard to build a stone plow: More difficult agriculture means less food and reduces the population farther. Many areas revert from agricultural villages to hunting/gathering.
  • Smelting and metalwork can take places only in areas rich in alternative fuels.

The upshot: Many places that were rich become poor, trade decreases, and trade routes change. Fuel becomes a valuable commodity. Kings' treasuries...and control...dwindle as folks work harder and longer at basic subsistence instead of wealth-producing activities. Many nations shrink or dissolve back into hunting-gathering tribes.

Some places that were poor benefit from their newly-valuable peat/oil deposits, but that doesn't outweigh the mass starvation caused by the tremendous decrease of agriculture productivity. Only the fuel princelings retain defended villages, and trade with tribes: Food for fuel. Warfare between nations becomes obsolete when the nations are gone. Mobile tribes downshift to nuisance raiding and horse/cattle/fuel theft...after all, what is there on the endless steppe that is really worth fighting for?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Jun 30, 2020 at 2:48
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    $\begingroup$ I don't think the jump from "wood not being renewable anymore" to "agriculture is dead" is appropriate. Thats a slippery slope fallacy. Agriculture includes the domestication of animals, which would become more crucial as their bone now becomes an alternative for tool making. The lack of wood creates a demand, don't underestimate that demand. $\endgroup$
    – V. Sim
    Commented Jun 30, 2020 at 21:27
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    $\begingroup$ @V.Sim - edited to address your comment. $\endgroup$
    – user535733
    Commented Jul 1, 2020 at 1:52

Welcome to stone age warfare, where you weapons are stones, which you can throw with your hand or using a slingshot.

No more wars then? Of course not, without wood you will hardly have walls, maybe some few meter high bare stone walls, but nothing imponent. Sure, there are examples of megalithic walls built with just large stones, but without doors building a wall becomes a futile exercise, unless the goal is self starvation. And without wood you cannot even work metals.

The most logic defensive architecture becomes a moat with the access path blocked, when needed, with a stone made barrier.

  • $\begingroup$ Why cant you work metal without wood? If it fuel you are thinking about there are alternatives such as dung or peat. $\endgroup$
    – lijat
    Commented Jun 29, 2020 at 5:39
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    $\begingroup$ @lijat you need high temperature to cast metal. Dung or peat would be used for cooking or to not freeze (hard problem if you don't have any house anymore), but it isn't as good as wood to reach high temperature. $\endgroup$
    – Kepotx
    Commented Jun 29, 2020 at 6:16
  • $\begingroup$ @Kepotx Coal on the other hand... $\endgroup$
    – Douwe
    Commented Jun 29, 2020 at 11:14
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    $\begingroup$ This is sort of what happened to the Easter Island civilization that built the enigmatic monuments there, after they cut down their last tree. Unfortunately we don't know much about the details because their stone-age descendants didn't have any way to preserve their history. $\endgroup$
    – workerjoe
    Commented Jun 29, 2020 at 12:39
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    $\begingroup$ Walls without doors still takes you from being vulnerable from any angle to (primarily) being vulnerable from a choke point. I imagine any military unit would much prefer that to being out in the open when defending against a significantly bigger army. That basically follows the same reasoning as a moat, except for the trade-offs between a perimeter of wall vs water (if not both). $\endgroup$
    – NotThatGuy
    Commented Jun 29, 2020 at 12:48

Warfare dissappears. Fighting still exists, and in fact is all over the place as people start starving, but war (organized fighting by armies led by commanders working for a ruler) is dead. You and your neighbour fight. Your country and your neighbour country engage in war. No countries = no war.

At the first moment, fortified cities and fortress all became suddenly impregnable. Walls are standing still and reinforced wooden doors can easily last centuries. However, the attacking side has no siege towers, no rams... not even ladders! There's no way to take your objectives except by siege. But that was almost already true before, so nothing has changed... except that now you can't get enough chariots, carts, wagons and what else to make your supply trains. And an army march on its stomach, as Napoleon said.

Also, navys are out - and maritime commerce and fishing is out too. The sea saltwater is poison to wooden ships. They don't last much, and when the last tiny boats are too rotten to float anymore, humankind is denied acces to water masses, except in small totora boats.

As tools made of wood start to break, replacements are made with bones (horse or oxen), or are built entirely in metal. Lack of fuel for fires is a much major problem. Soon, fire is seen as a kind of magical mystical force to revere instead of a commodity. Most food is eaten raw, and alternative ways of cooking, such as salting and curing processes are increasingly common. Using polished metals to concentrate sunrays in solar cookers becomes the new normal, and every piece of silver than can be found is used that way.

Transportation hits a crisis as cart wheels break and nobody know how to repair them. The only solution is using (way smaller) metallic wheels. The rest of the chart is made of totora, esparto or hemp atached to a mettalic or bone frame to provide stiffness, or it is a simple net hanging between two metallic rods. In any case, commerce is made only locally, and states disintegrate into poleis.

Once civilization reaches a new equilibrium state and gets used to the "new normal", war can resume as another one of our usual routines. Every city-state can recruit an army - there are no standing armies - and wage war against its neighbours (no farther than that, since there are no navies). War is seasonal, since men must return in order to harvest. Main weapons are maces, hammers or axes of bone and stone or metal, only commanders are rich enough to have a sword (too much precious metal for just one weapon). Bows are replaced with slings. Armours are made of leather, cloth, fur or even paper, reinforced with bones, seashells or metal plates or scales. Polearms are gone, which all in all benefits horsemen. Stone bridges become strategical critical points. If one is ever distroyed, it cannot be rebuilt, incommonicating whole regions on a permanent basis.

  • $\begingroup$ The distinction between "war" and "fighting" seems academic to me. To me at least, "fighting" and "war" relate to each other like "tree" and "forest". If no country means no war, what exactly was the war on terror about? $\endgroup$
    – Douwe
    Commented Jun 29, 2020 at 10:38
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    $\begingroup$ @Douwe Political propaganda? A bar fight or a lovers quarrel are not a war. War is politics with other means. And a tree is a living being, but a forest is a biome. $\endgroup$
    – Rekesoft
    Commented Jun 29, 2020 at 10:42
  • $\begingroup$ I meant that a lot of people fighting in one place will be called a war. Just like a lot of trees in one place will be called a forest. You really don't need a country to have a war. We've had wars on anything from Al Qaida to obesity. You might not find the war on obesity a proper war, but the one with Al Qaida ticks all the boxes I would think. $\endgroup$
    – Douwe
    Commented Jun 29, 2020 at 10:48
  • $\begingroup$ @Douwe That's why I don't say "country". I say "state". The Osama Bin Laden killing was not a war. The war against Isis was. Because the Islamic State could be unrecognized internationally, and its frontiers and economy quite fuzzy, but it was certainly real enough for those living in there. You need some quite of structure and organization to wage war. The very minimum to consider some brawling "a war" it's organized battles between consolidated organizations such as Mexican cartels or revolutionary organizations such as FARC. There's in no warfare in improvised fighting. $\endgroup$
    – Rekesoft
    Commented Jun 29, 2020 at 11:04
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    $\begingroup$ Also, since it still seems like an academic distinction to me, let's just go with the formal definition and be done with it $\endgroup$
    – Douwe
    Commented Jun 29, 2020 at 11:18

The main problem will be the lack of firewood. Coal, which has been used in Europe since at least Roman times can replace it, but will become rather expensive and may be mainly used for metalworking, while the poor must burn peat or dung for heat and oil or candles for lighting.

As for bows, horn and bone bows have been used in bows, usually in combination with wood, but composite bows entirely made from horn, bone, and sinew are quite possible. Bog wood can also be used. Even so, slings may become more fashionable, as they require no wood.

Incidentally, if you treat wood well - e.g. oil it regularly - it can last centuries, if not millennia. As time goes by, wooden bows and furniture will become rarer and more valuable, but this will take a long time. Wheels and barrels will have to be made entirely from metal rather than from metal-banded wood.

For siege weapons, you could make ballistas and onagers from bone, rope, leather, and sinew. It may not be possible to make them quite as big as wooden ones, except perhaps with whale bone, but you can make them. It might be possible to stiffen rope with resins or pitch to replace timber. Rams can be made entirely from metal or possibly stone bound with metal.

A major change will be that large ships will be nigh-impossible to make unless you master the art of steel ship-building. You will be limited to boats made from bone and hide, like the Inuit do or did.

Addendum: With the lack of wood, the ceramics industry will likely blossom, including creating ceramics that harden without heating, like the very strong Roman concrete, and improving glass. Brick and concrete houses will replace wooden houses, and ceramic pots will replace wooden barrels. Ceramic weapons and glass weapons will supplement or even replace metal ones, if metal becomes expensive (which would especially make metal armor very expensive).

  • $\begingroup$ hide boat almost always have a wooded frame, even if just branches. it also becomes almost impossible to mine coal as you would be very limited in tools and not be able to braces mine shafts so you would be limited to surface deposits. Same for mining iron ore. $\endgroup$
    – James Cook
    Commented Jun 29, 2020 at 14:04
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    $\begingroup$ @JamesCook: The Inuit umiak boats (as well as kayaks) are made from whalebone as often as wood. There is very little wood in Greenland. The coal most often used in medieval times was 'sea coal' from seams exposed by the ocean, which apparently was quite common (follow link in the answer). And, lacking wood, you can brace mine shafts with bricks and mortar. $\endgroup$ Commented Jun 29, 2020 at 14:16
  • $\begingroup$ @KlausÆ.Mogensen, note that brick-reinforced mineshafts will be vastly more expensive to operate than wood-reinforced ones. I expect that the resulting increase in the cost of coal will keep the industrial revolution from ever happening -- with steel being so rare and expensive, you never get the feedback cycle of the coal-mining and steel industries reinforcing each other. $\endgroup$
    – Mark
    Commented Jun 29, 2020 at 21:52
  • $\begingroup$ @Mark: Sure, brick reinforcement will initially be more expensive than wood-reinforcement, but with the lack of wood, the brick and ceramics industry will blossom, and Roman concrete could be reinvented, allowing for very strong construction. $\endgroup$ Commented Jun 30, 2020 at 8:12
  • $\begingroup$ @KlausÆ.Mogensen roman concrete can't just be reinvented anywhere is uses a specific mineral that only occurs in a few places. and they will not be making great brickwork without wood, making mortar requires a fuel source as does fired bricks. a coal mine will be lucky to produce more fuel than it consumes. you also have hte issue of what they are mining with, no wood for tools means no picks. $\endgroup$
    – John
    Commented Jul 1, 2020 at 2:41

Your "generic medieval setting" quickly becomes a nomadic steppe setting.

When all trees disappear, it is logical to assume that they will be replaced with grasses. This might be difficult to imagine for Western Europe, but in other parts of the world the lack of trees is common, and we shouldn't look too far to see what the warfare would look like.

First, traditional agriculture would become difficult, and many permanent settlements would become unsustainable. On the other hand, the population of grazing animals is set to explode, and humans would take advantage of that. A horse warrior, armed with a sword and bow will become a standard in the aftermath. Arrow shafts can be made from sturdy grass stems, but for spears and other polearms grass would be inadequate.

Remaining wood would become expensive, but still quite common for the several decades afterwards. This means that defensive structures and offensive contraptions like catapults would still be widely available. After all wood will rot, earthworking would be the main way to conduct siege warfare.

Sites of natural resources like coal and peat would become contested. The one who controls the fuel can control metallurgy, and reliance on iron and steel would set to increase.

  • $\begingroup$ Bow? I suppose there are horn bows... $\endgroup$
    – NomadMaker
    Commented Jun 30, 2020 at 5:03

War, despite what many would have you believe, is largely about logistics. So let's look at how societies would be affected, because that will greatly affect your supplies, movement, and more.

Like most other answers, I agree that the disappearance of trees would result in a complete collapse of society. The only thing I might say differently is how society collapses.

The first thing I think people may have missed is...

Without trees (and their roots) soil will erode

This will wreak havoc on almost every food source available to humans.

  1. Fertile soil will begin eroding, meaning domesticated plants won't grow.
  2. Many types of birds will die out or be severely reduced in numbers by a lack of habitat.
  3. Many types of animals who hide in forest environments will die, and predators of those animals will attempt to hunt livestock.
  4. Soil from the mountains will erode onto grass fields, devastating grazing animals in many places.
  5. Dangerous mudslides will occur burying towns, roads, livestock...
  6. Dirt will go into rivers and often clog them, killing many types of fish we rely on to eat.
  7. Harbors will be silted.
  8. Seashore ecosystems will also be devastated by the large influx of new minerals and components.

Soil erosion based on clear cutting is a likely cause of many civilization collapses in our history (think the Easter Island civilization, possibly the Mayan civilization, and others); how much more so the complete disappearance of trees?

The only source of food that potentially wouldn't be effected would be ocean fishing... but, as has been made clear in other answers, ships won't be able to function without wood for repairs for long.

Effects on Humans and Responses to Responses

At this time I'll take a moment and ask: during the current pandemic when toilet paper was being hoarded, fights broke out over it at the super market... so what would happen if the thing that was scarce was what you cooked with, was what you did your job with, was what kept you from freezing to death in the winter?

In our world, it would be like if oil suddenly disappeared. Yes, we have other sources of energy, but are they enough? There are some movie franchises, methinks, that would argue otherwise.

Growing Food

Obviously, growing food will quickly become a problem based on the above discussion of soil erosion and logic from other answers. I won't duplicate that here.

Processing food

In the medieval period, wheat was ground into flour on an industrial level by water wheels and wind mills. Both of which were usually made of wood. And both of which endure large mechanical stresses on a daily basis. They would break rapidly, meaning that what food stores you might have would soon need to be processed manually, which, while possible, greatly reduces efficiency.

Cooking food

Perhaps more immediately, cooking will become a problem.

At the time that trees disappeared, many people would be relying on wood for heating their food. Much of the time they will have stocked up some amount of firewood, but not an outrageous amount: there's a whole forest right there, why hoard wood? In cities they might have less, as they need to buy the wood instead of chopping it down themselves/with their community.

After going through the few days of firewood people in those areas have stored, what will they do? If peat etc are not currently a part of their heating strategies, then they'll have to burn finished goods for heat. Furniture, tools, abandoned buildings, all start getting thrown into the fire. Civilization is eating itself.

Peat, Coal, etc

Even in places where peat is burned, the huge influx of demand will create shortages. Could those areas scale up production to meet demand? When they can't mine more because they can't use wooden frames for holding up the shaft? When other groups/cities/countries are attacking them to get hold of the fuel sources they do have?

Heating residences

Next, there's heating. Without wood, many northern climes would become largely uninhabitable except by very few. If you can't start a fire, most of your run-of-the-mill peasants are going to be in big trouble.

Responses to these challenges

Once a baron/lord/king realized that trees were gone, they might attempt to march an army over to the nearest coal mining nation. But as I said at the beginning, war is about logistics.

So: how would he transport supplies? Weapons? Armor? Previously he would have used carts and wagons. Now, though, when an axel breaks, you can't just go off the road and chop down a tree to make a new one.

Worse, due to soil erosion, the roads will be in terrible condition. There will be mud, mud, mud, for as far as the eye can see (if he's lucky and this doesn't happen in the winter). Amounts of clean water large enough for an army will be hard to find, leading to all kinds of infections and diseases.

Once he arrives, how will he create siege engines? Dig sapping tunnels? Those were usually built on the spot. As other answers have noted, cities will be largely impregnable.

Maybe he can just go straight to the mines... Perhaps, but don't you think the existing rulers will have taken all the peat/coal behind walls? Ok then, maybe he can just guard the mine while his soldiers mine the materials. Great, how will he transport his ill gotten gains back to his people? Over those bad roads, with too few carts that have been cannibalized endlessly, pulled by draft animals with no grazing, led by men with dysentery.

So he gets home, only to find his people (with the help of his desperate garrison) have ransacked his castle in order to find things to burn. Peasants are now dying in droves, and have found a new leader while he was gone.

And so on.

Conclusion: Effects on Warfare

The effects on warfare would be immediate and drastic: there would be a lot of it, and it would be largely ineffective. Bunches of failed forays into other countries, which quickly devolve into populace control, until, finally, armies as a concept would cease to be viable.

Any civilization that lasted long enough to worry about how heavy an all metal pike is would count itself lucky. It would be a super power in its (limited) area, and organization, supplies, and numbers would easily overcome any bedraggled, starved enemies. Technological and societal advance would slow to a crawl as stone and metal became the only feasible building materials. It would be extremely vulnerable to starvation, bad weather/seasons, and disease.

As far as armaments and tactics go, many other answers, and the question itself, covers many feasible possibilities. But, as a short, speculative list:

  • Ranged weapons would be confined to slings.
  • Sieges would center around waiting a city out
  • Cavalry would become much less effective without wood for saddles and grain for horses
  • Metal weapons would become even more expensive due to the difficulty in creating more
  • Pitched battles, as a result, would likely have more survivors, and may become largely for display (though that is just pure speculation)
  • $\begingroup$ I don't see why soil should erode anywhere except in vicinity of mountains (and dry forest areas, which would become "dust bowls" until grasses would stabilize them). Moreover, an increased amount of silt in rivers should increase the fertility in medium term. $\endgroup$
    – Alexander
    Commented Jul 1, 2020 at 16:14

without wood you would have a hard time cooking food. In certain areas you might be able to use animal dung if there are large herds of herbivores.

Your ability to make tools would be very limited. You could make hand held stone axes and stone knives, but no axes, spears, or bows.

You might be able to find some surface deposits of coal and iron ore, but with only hand held stone tools they will be hard to mine. Without wood for shoring underground mining become almost impossible.

You would also have an ecological disaster as many animal depend on trees and forests. Humans would have a difficult time simply surviving as they would lack protection form predators, would have difficulty hunting, or even protecting crops from wild animals.


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