When the famous Carthaginian general Hannibal catapulted poisonous snakes at enemy ships

In the early second century BCE, the power vacuum left by Alexander’s broken empire allowed small kingdoms across Asia Minor to fight for control of coastal territory and regional trade routes.

Among the most prominent rivals were Bithynia, ruled by King Prusias I, and Pergamon, led by King Eumenes II.

Their dispute was about who would control the trade ports along the Propontis and secure influence over nearby cities.

The Propontis, now known as the Sea of Marmara, which linked the Black Sea to the Aegean, was important for both trade and military movement.

Eumenes had strong ties to Rome and positioned himself as a loyal ally of the Republic on order to use this relationship to pressure weaker neighbours into submission.

He had previously supported Rome in the war against Antiochus III and received additional territory in return.

Unfortunately, Prusias was facing a growing lack of allies, so chose to counter Eumenes by launching a naval campaign.

His own fleet, however, lacked the size and training of its opponent. To offset this, he relied on the skill of his most experienced guest, who was Hannibal.

By that time, Hannibal had lived in exile for nearly two decades. Following his defeat at Zama and increasing pressure from Roman officials, he had fled Carthage and had found refuge at the court of Prusias I.

Rome had demanded his surrender more than once, and his name still stirred anger among Roman leaders.

Instead, Prusias welcomed him not only for his military skill but also for his hatred of Roman power.

Because Hannibal faced a stronger enemy navy, he looked for a method that would avoid direct engagement.

He suggested gathering live venomous snakes and sealing them in clay jars. Then, during battle, the jars would likely be launched onto enemy ships.

The goal was to cause panic rather than to kill. Since warships offered limited space, and any unexpected disturbance could cripple discipline, by filling the jars with snakes, Hannibal turned ordinary projectiles into weapons of a fear tactic.

He had ordered his men to collect dozens, perhaps hundreds, of snakes (likely vipers such as Vipera ammodytes, which modern scholars suggest may have been used due to their aggressive temperament and regional presence) and to prepare the jars without alerting the wider fleet.

At first, Prusias and his officers hesitated, as the idea sounded absurd, even dangerous.

However, Hannibal explained the logic: enemy crews would not know the jars’ contents and they would probably assume the jars held fire or stones.

When the jars broke and snakes slithered out across the decks, fear would spread faster than wounds ever could.

As a result, he had created a two-stage plan. First, the Bithynian fleet would keep its distance and bombard the enemy with snake-filled jars fired from torsion-powered catapults that had been adapted for naval use.

Once confusion took hold, the ships would close in and attack during the breakdown in command that followed.

The battle began as the Pergamene fleet advanced, while the Bithynians held back.

Instead of engaging immediately, they launched the jars from ship-mounted catapults.

At first, nothing seemed unusual. The jars shattered on impact, but no fires broke out and no structural damage appeared.

Then, the snakes appeared and, at once, panic erupted on the enemy ships. Sailors shouted warnings, dropped weapons, and ran across the decks to avoid the creatures.

Some fled below deck, others jumped into the sea. Officers lost control of their crews, and commands could no longer be followed, and the fleet’s formation fell apart.

Instead of taking advantage immediately, Hannibal waited for signs that the chaos had spread as far as possible.

Only then did the Bithynian ships close the distance and begin boarding attacks.

They encountered little resistance, as most enemy sailors no longer followed orders, and many had already abandoned their positions.

Some later accounts claimed Eumenes may have been present during the battle and narrowly escaped, though no ancient source confirms this detail.

Few sailors were likely bitten, and even fewer probably died. But, the snakes did not need to cause serious harm.

This is because ancient ships required precise teamwork, especially in battle. Once that broke down, no advantage in numbers could restore order.  

Hannibal’s plan worked because it attacked morale, routine and discipline. Snakes, though not especially lethal in most cases, disrupted all three.

On land, troops could spread out or retreat. At sea, where space was limited, fear spread fast and left entire crews unable to act.

As a result, Bithynian ships defeated a larger enemy without the need for superior weapons or training.

The disruption allowed them to board ships easily and win hand-to-hand engagements against sailors too terrified to fight.

Years earlier, he had used terrain to trap Roman forces at Lake Trasimene and Cannae.

Now, with no control over terrain, he used fear instead. He turned the battlefield into something unpredictable and gave him an advantage.

Interestingly, no other recorded commander seems to have repeated the tactic, which suggests it only worked under precise conditions.

Roman authors, especially Sextus Julius Frontinus, whose Strategemata (Book 2, Chapter 13) credited Hannibal with the tactic, did not name the opponent or give details about the campaign.

Later writers such as Aulus Gellius in Attic Nights (Book 7, Chapter 3) repeated versions of the story, but their accounts lack specific details.

No local records from Bithynia or Pergamon survive to confirm the event. Still, the core details appeared plausible.

Hannibal did live in exile at the court of Prusias I and he did advise him during military campaigns against Eumenes II.

Regardless, many Roman allies still hunted him, and any opportunity to harm Rome’s friends would have appealed to him.

The unusual nature of the tactic may explain why it survived in Roman sources, since they often admired Hannibal’s cleverness, even while condemning his cause.

Roman generals trained with Frontinus’ works as examples of fieldcraft and problem-solving.

Therefore, Hannibal’s snake jars became part of this tradition, because of the way rather than because of their violence, they reversed the odds.

It is important to note that no archaeological evidence that confirmed the event has yet been found.

However, the consistency of the accounts with known historical facts, and the psychological logic behind the plan, make it likely that something similar did occur.

Some modern historians considered the tale exaggerated. If the number of snakes or jars was inflated, the strategy's main idea still seemed likely.

Roman authors kept it as a lesson rather than as fantasy showing how creative tactics could defeat greater forces when used with careful timing and planning.

In the months after the battle, Roman pressure on Bithynia continued. Although Rome had already demanded Hannibal’s surrender during earlier phases of his exile, they pressed their demand again.

Prusias eventually gave in to the request. To avoid capture, Hannibal took poison and died around 183 BCE, and he reportedly said that he would not fall into his enemies' hands.