Ancient chemical weapons and weaponized animals (think flaming pigs) didn't have the devastating reach of our warheads and delivery systems today, but they were terrifying nonetheless. Some of these unconventional weapons, on a primal fear level at least, may have been even more terrifying than the weapons of today—when they worked.
1. SIEGE OF BALA HISAR, CHARSADDA, PAKISTAN, 327 BCE
Much of the evidence for ancient weapons is in written sources of questionable accuracy, but in 1995 archaeologists found a small burned ball in a ditch outside the Bala Hisar (meaning High Fort) in Charsadda, Pakistan, from the 4th century BCE. The ditch was part of the defenses during the time of Alexander the Great's siege of the fort in 327 BCE.
Chemical analysis found the ball was a man-made object composed of the heavy mineral barite and flammable resins from various pine trees. Archaeologists believe it was lit on fire and thrown from the ramparts onto the besieging army, making it south Asia's earliest fireball.
2. THE LIMESTONE DUST TEAR GAS OF QUINTUS SERTORIUS, PORTUGAL, 80 BCE
Plutarch tells how Roman general and rebel Quintus Sertorius defeated the Characitani in modern-day Portugal by fashioning makeshift tear gas out of lime dust and earth. The Characitani were holed away with their booty in impregnable limestone caves laughing at Sertorius. While they were hooting, Sertorius was figuring out that the lime dust kicked up by his horse was being blown toward the caves by the cool north wind, so he had his soldiers collect a large quantity of the fine lime dust and mound it up underneath the faces of the caves.
The Characitani thought it was some pathetic, budget attempt to build a ramp to reach them and laughed it off, but the next morning when the wind began to blow, Sertorius's men stirred up the dust mound, breaking up the clumps, even trotting their horses through it to get the particles good and airborne. Huge clouds of the caustic lime dust were blown into the caves. With no source of fresh air other than the cave openings, the Characitani had to choke on lime dust, which irritates the eyes and lungs and causes alkaline burns to mucous membranes if not washed off immediately. After two days of such suffering, they surrendered to Sertorius on the morning of the third day.
3. THE NEW AND IMPROVED LIMESTONE DUST TEAR GAS OF CHINA, 178 CE
Emperor Ling of the Eastern Han Dynasty may have been a dissipated, corrupt, eunuch-dependent wastrel, but he had some great generals. With widespread famine and resentment at his failed leadership instigating regular peasant uprisings, the emperor really needed them, too. One of the peasant revolts in the Guiyang Commandery (modern-day Hunan province) in 178 CE was suppressed by lime dust, only the Han troops made it portable.
According to the court history of the period, the Hou Han Shu, one Yang Hsuan, governor of the Lingling prefecture, kitted out dozens of chariots with bellows and lime powder. The lime chariots advanced, blowing the corrosive dust "according to the wind" at the rebels encircling them. While the peasants were choking and blinded by the powder, Yang's men tied incendiary rags to the tails of horses, lit them on fire, and drove them into the enemy lines.
With the peasant army scattered and in chaos, Yang's bowmen picked them off easily and the rebellion was crushed.
4. THE BURNING PIGS OF MEGARA, 266 BCE
Turning a living animal into an incendiary device is a diabolical form of "biological" warfare, but an effective one, as seen in the Siege of Megara in 266 BCE. Polyaenus notes in Stratagems in War that it was flaming pigs that broke the siege. Antigonus II Gonatas, King of Macedon, brought two dozen Indian war elephants to besiege the city, but the Megarans:
daubed some swine with pitch, set fire to it, and let them loose among the elephants. The pigs grunted and shrieked under the torture of the fire, and sprang forwards as hard as they could among the elephants, who broke their ranks in confusion and fright, and ran off in different directions.
Antigonus learned his lesson, though. He instructed his Indian elephant trainers to raise them next to pigs so they wouldn't freak out at the sound of them in battle.
5. HANNIBAL'S SNAKE BOMBS, 186 BCE
The great Carthaginian general Hannibal Barca, who is probably best remembered for his attempt to cross the Alps with his own war elephants, found himself in reduced means toward the end of his life. He'd gone into voluntary exile when the Romans got antsy over his excessive competence and wound up traveling around the Mediterranean and Asia Minor, trying to stay out of Roman hands and offering his military genius to various kinglets.
In 186 BCE, King Prusias I of Bithynia, then at war with King Eumenes II of Pergamon, put Hannibal in charge of his navy. It was a meager fleet, vastly outnumbered by the Pergamene ships, so Hannibal had to come up with a stratagem to ensure his side's victory. A key part of his cunning plan was putting large numbers of live venomous snakes in earthenware pots and distributing them to his ships. He directed the captains to focus on attacking King Eumenes's ship and let the snakes defend them.
The coordinated attack almost worked—Eumenes wasn't captured or killed, but he did have to flee—and when the rest of the Pergamene navy bore down on the Bithynian ships, the Bithynians started lobbing snake pots at them. Suddenly finding themselves ankle-deep in extremely pissed-off and bitey snakes, the Pergamenes beat a hasty retreat.
6. THE BURNING CHICKEN FEATHERS OF AMBRACIA, 189 BCE
When the troops of Roman consul Marcus Fulvius Nobilior besieged the Greek town of Ambracia in 189 BC, the defenders proved remarkably effective against the Roman battering rams, so the general decided to go under the wall instead. The Ambracians soon realized, despite Marcus's efforts at concealment, that tunnels were being dug, and they started digging their own tunnels, until the twain met under the city. At first the confrontation was conventional—they tossed spears at each other—but when shields and wattle screens deflected the weapons, the defenders got crafty.
In Histories 21.28 Polybius describes how the Greeks took a jar as wide as the tunnel, bored a hole in the bottom and inserted an iron funnel into it. They then filled the jar with chicken feathers, lit a fire next to the mouth of the jar, and topped it with an iron lid peppered with holes. When they got to the enemy's position, they placed the jar in the tunnel and filled in the empty space around it, creating a block with only two holes on each side just wide enough for spears to be thrust through to keep the Romans from messing with the jar.
They then took a pair of bellows such as blacksmiths use, and, having attached them to the orifice of the funnel, they vigorously blew up the fire placed on the feathers near the mouth of the jar, continually withdrawing the funnel in proportion as the feathers became ignited lower down. The plan was successfully executed; the volume of smoke created was very great, and, from the peculiar nature of feathers, exceedingly pungent, and was all carried into the faces of the enemy.
Burning feathers don't just smell painfully acrid. Combustion of the cysteine in feathers releases toxic sulfur compounds. This was the first known use of poison gas against a Roman siege tunnel and while it worked like a charm in the moment, it wasn't enough to defeat the Roman army. Shortly after the weaponized burning feather incident, a group of envoys from Athens and Rhodes convinced the city to surrender to Marcus Fulvius.
7. THE SULFUR GAS OF DURA-EUROPOS, 256 AD
The outcome was very different when the shoe was on the other foot about 445 years later. This time it was the Romans defending the city of Dura-Europos in modern-day Syria, and their besiegers, the Persian Sasanian Empire, digging tunnels under the city's massively thick walls. Roman troops dug a counter tunnel, apparently hoping to intercept them from above, but the Persians heard them coming and hatched a cunning plan.
When the Romans broke through into the Persian tunnel under Tower 19 of the city's western wall, the Sasanians lit a fire and threw sulfur and bitumen on it. They may have used a bellows like the Greeks did to direct the fumes, or they may have taken advantage of the chimney created when the Romans dug down to intercept them. Whatever they did, it worked. The Romans were gassed to death, the sulfur dioxide turning into sulfurous acid in their lungs. The skeletal remains of 19 Romans and one Persian (perhaps the man who lit the fire got a little too close?) were discovered stacked in the Persian tunnel during archaeological excavations in the 1930s. A jar coated with pitch residue and yellow sulfur crystals was found near the bodies.
8. THE (FAILED) SULFUR GAS OF PLATAEA, 429 BCE
King Archidamus II of Sparta tried to deploy the deadly gassing power of sulfur, pitch, and fire against the city of Plataea in 429 BCE during the Peloponnesian War, but conditions were not as propitious for him. There was no tunnel, for one thing, so this was going to have to be an open-air gassing, dependent on the whims of the wind. If it stood any chance of working, it was also going to have to be far bigger than a little jar fire.
As Thucydides tells it in his History of the Peloponnesian War, the Spartans spent 70 days building a massive earthwork framed in timber. Initially the plan was to breach the city walls, but the Plataeans weren't just going to wait that out. They added to the wall in front of the mound, matching its height as it grew, while stealthily digging the earth out of the bottom of the mound.
Archidamus saw the futility of this exercise and changed gears. He had his troops throw bundles of brushwood into the gap between the mound and city walls. When that was full they started throwing the wood into the city itself. Then they set the whole thing ablaze complete with sulfur and pitch additives. Thucydides says "the consequence was a fire greater than any one had ever yet seen produced by human agency," comparable to a forest fire.
The weather did not cooperate, however. The wind didn't blow the deadly gas into town and soon a thunderstorm put out the great bonfire.