For most of human existence, our primary weapons have depended on one or more of three principles: sharp edges, kinetic force, and fire. But what options lie beyond that circle?

To the general public, this is the territory of “weapons of mass destruction.” The modern military acronym here is CBRN: chemical, biological, radiological, or nuclear. (The latter two are not redundant; you can poison people or landscapes with radiation by means other than a nuclear explosion.) We have lots of ways of causing mass destruction — in fact, that phrase originally referred to the World War II practice of massive aerial bombing campaigns with conventional explosives — but it’s true that those four have the potential to wreak havoc on a different scale. Many post-apocalyptic stories begin with the premise that one of them has destroyed the world, and the characters are living in the aftermath.

Of that deadly quartet, the R and the N are genuinely new. Although natural radioactive decay happens all the time — including in your own body, right now! — we only began to understand radioactivity at the very end of the nineteenth century. Then it was decades more before we developed materials powerful enough to make the idea usable for the purpose of warfare. Since then, nobody has actually deployed radiological weapons on an operational scale; while some have been created, they’re not a central feature of our combat.

Nuclear weapons are a different story, and rather famously so. Though only two have ever been detonated in war, they exist in large numbers and have played a major role in the international balance of powers for the last eighty years. The threat of their use is real, as is the risk that someone might be aggressive enough to follow through on the threat. The outcome of that would depend on a lot of factors, including not just the scale of the attack but where it’s aimed and what the weather is doing at the time. (May we never learn the answer outside of fiction.)

But what about those first two? What about the C and the B?

Depending on how you define it, chemical warfare is prehistoric in origin, dating all the way back to the use of poison arrows in hunting. That’s pretty inefficient for combat purposes, though — especially against armored opponents — so although poisoned weapons continue to show up here and there in the historical record, they’ve never been a significantly load-bearing part of our tactics.

Instead, generals of the past wanted to poison the environment somehow. On the battlefield, this might take the form of toxic smoke, created by burning a variety of noxious substances. The challenge here, then and now, lies in figuring out how to make sure the enemy breathes it in and your own army doesn’t. In modern times we can accomplish this by using artillery to heave the source of the smoke far enough away and/or supplying our own troops with protective gear, but in the past you had to rely on things like the direction of the wind (which might change!) — or, sometimes, you could drop it into a tunnel the enemy was digging, and thereby contain the effect.

Alternatively, poison the food or water. Food is harder to arrange, but water can be done; there’s a Greek tale that Solon of Athens dropped hellebore roots into an aqueduct, and let the flow carry the toxin into the city he was besieging. (Though if he had access to the aqueduct, I do wonder why he didn’t just cut off the supply entirely, which is probably even more effective.) More often, water gets poisoned not with a chemical but with a biological agent: a dead body, ideally one that died of some horrible infectious disease. Attackers might launch these via catapult into a site under siege; retreating defenders might leave them behind to deny resources to the enemy.

Biological warfare is also ancient. Our earliest record is of the Hittites driving victims of a disease (possibly tularemia) into enemy lands for the purpose of spreading contagion. But it’s difficult to use disease as a weapon of war if you don’t properly understand how it works in the first place; early instances depended more on the idea that the stench of the corpse would make people sicken than on any modern-looking theory of germs. Since it also requires having infected sources ready to hand, the risk that this will wind up harming your army as much as the enemy’s is non-trivial. Once again, modern science and technology have made this route substantially more viable than it was in the past.

Which brings us to the spec-fic side of things. In SF, of course, we generally assume a high understanding of chemistry, biology, and nuclear science, which opens a lot of doors on this front . . . and yet, the deep-rooted love of pew-pew shooting between ships in space means that I’ve seen relatively little in the way of military-focused SF that really exploits these angles for warfare. (Which may very well be sample bias on my part, as milSF is not something I read in large quantities. If so, let me know!) It seems to show up more often as a feature of dystopian settings, where designer agents are used on a local terrorism scale instead of that of conventional warfare.

In fantasy, the question becomes kind of intriguing. What would count as an unconventional weapon in such a world? Magic could take us in directions entirely unrelated to the CBRN of modern concerns, e.g. mind control. Or perhaps it’s something like biological warfare, except that disease operates on a framework other than germ theory, as discussed in Year Three, which makes it more amenable to weaponized use. There are also multiple stories that posit some kind of contagious spiritual and bodily corruption, like the Blight of the Dragon Age franchise or the Shadowlands Taint in Legend of the Five Rings — though I don’t offhand recall any instances of the monstrous enemy trying to stealthily spread that corruption to a target population. They just overrun it with conventional war instead, and the corruption is a side effect.

Magic might also create something that operates like radiation, without actually being about the decay of isotopes. I’ve seen a number of settings where the landscape in a certain area has been warped by magical effects (and perhaps continues to warp) — not surprising, given the radiological fears many authors grew up with during the Cold War. It tends to be the aftereffect of battle, though, rather than an attack in its own right, a la the neutron bombs we’ve developed but not used.

Even if war isn’t the focus of a story, these things can still play a role, either through their lingering effects in memory/the population/the landscape, or through fears of what might happen next. Or you could stick with the tried and true: sharp edges, kinetic force, and fire!