The Bizarre Roman Emperor Who Declared War On The Sea

Caligula (full name Gaius Caesar Augustus Germanicus) ruled as emperor of Rome from AD 37-41. His nickname (apparently meaning “little military boot”) came from the tiny soldier’s costume he wore when he was small. He was 24 years old when he became emperor.

To set the scene a little bit: Julius Caesar attempted to invade Britain in 55 and 54 BC. Both campaigns ended without really any major result and without establishing any tangible presence for Rome. As such, Britain remained a goal for emperors to achieve by the time Caligula ascended to the throne.

Adminius, son of the British king Cunobelinus, had either fled or been driven out of Britain and submitted himself to Caligula. According to the Roman historian Suetonius, Caligula presented the surrender as though the whole island had yielded to Rome.

In AD 39/40, Caligula marched toward the Rhine frontier and toward the North Sea or Channel coast with a large number of troops. It is possible that he undertook German campaigns; perhaps disciplinary action in the legions, or maybe even preparations for the conquest of Britain, or perhaps all three. In any case, he and his army eventually arrived at the coast.

Suetonius writes that they were drawn up in order of battle, the catapults aimed out over the sea, all that, when suddenly Caligula ordered them to halt, then instructed them to pick up shells. The soldiers promptly stuffed the shells into their helmets and uniforms. Caligula then declared the shells “spoils taken from the Ocean,” Suetonius writes.

Nearly 200 years later, the Roman historian Cassius Dio recounted that that after sailing out a bit, Caligula had come back to shore and sat on a high dais, then ordered the battle trumpets to be blown and his men to gather some seashells.

And yet popular retellings say soldiers stabbed the ocean with their swords; that archers shot arrows at the water; that catapults bombarded the waves; that Caligula formally declared Neptune an enemy of Rome. But none of that is mentioned by Suetonius or Dio.

It is possible that the idea that Caligula “punished” the sea was derived from a pre-existing myth about the Persian king Xerxes, who is said to have had the Hellespont (the modern-day Dardanelles) whipped when a storm destroyed the bridge that he built across it. Several centuries of retelling and conflation may have combined these two tales.

Another traditional interpretation takes the shell-gathering episode at face value: an emperor who had completely lost his mind and genuinely believed he’d bested the sea.. Yet, no one can ever pin the incident solely on madness.

Some historians believe a mutiny may have happened before the shell-gathering incident. Maybe Caligula’s troops refused to sail off to Britain, so Caligula told them to gather shells as a “surrogate” for the treasures they would take from the Britons. What fun!

The ocean was not merely water to the Romans; it was the end of the inhabited world, and reaching the ocean could itself be framed as the extension of Roman rule. It follows, then, that the shells as trophies from the ocean might have represented Rome’s reaching the limits of the world, rather than any actual conquest of the sea itself. Yet there are no extant texts saying such a practice was an actual ritual.

Suetonius called them conchae, or “shells.” Some scholars have suggested that the word actually hid a misunderstood military expression, like a nickname for small boats. In other words, he might not have been referring to seashells, but to ships.

Some later writers might have lumped together a few disparate incidents, including troops gathering for an invasion of Britain, an aborted embarkation, the surrender of Adminius, training in amphibious operations, and payoffs to the troops, and spun them into a single heroic tale; then they might have dropped the broader story and left only the bizarre detail of an emperor commanding his troops to gather shells and calling them spoils.

Caligula supposedly ordered that the collected shells be called spoils ‘owed to the Capitol and Palatine’ and announced that he would present each legionary with 100 denarii, dismissing them, as Suetonius records, to ‘go their way happy, go their way rich.’ (Maybe that was just a nice bonus for him, too!)

Caligula, in his idiosyncratic way, allegedly wanted to parade the spoils around Rome and even discussed having them honored with triumphs. There’s no way to be certain, though, whether he actually had wagonloads of shells carried through the city, or if there was any victory party, for that matter.

The biographer Suetonius noted that Caligula had a tall tower erected on the coast, equipped with fires which were to be lit from the summit at night. It may have been used to direct ships, to facilitate military transport, or merely to mark the location of the expedition.

Many scholars believe that the site is Boulogne-sur-Mer in northern France, where it was sensible to embark on a voyage to Britain. Other possibilities include the North Sea coast, the Rhine delta, and locations in what is now the Netherlands.

Suetonius, writing about 80 years after Caligula’s death, mixes imperial material with gossip, scandal, and even jokes, arranged around topics of vice. Cassius Dio writes close to 200 years later, drawing on earlier works that no longer survive, so some of the drama may have taken shape in the interim.

Caligula was assassinated in January AD 41. He was replaced by his uncle, Claudius. Claudius did finally conquer Britain, successfully invading in AD 43. But his own troops apparently hesitated to cross the Channel at first, so the idea of a mutinous army during Caligula’s reign isn’t totally implausible. Although Caligula’s preparations might have paved the way for Claudius’ successful campaign, it would be a stretch to claim that Claudius inherited a complete, finished invasion plan from Caligula.

The only things we can be sure of in this mess are that Caligula had troops assemble on a coast around AD 40, a battle-like ceremony happened, soldiers picked up items that the texts call shells, and Caligula called them the spoils of Ocean. Nowhere does it state he declared formal war on Neptune, or even instructed anyone to hurl themselves at the sea. Everything else is an educated guess. I’m still betting on his order to the soldiers to gather shells as a penalty for their reluctance to obey.

This content was created with the help of AI.