Even today, Caligula’s name is synonymous with madness and debauchery in power. During his four years as princeps, the emperor paid, in pro-senatorial eyes, dearly for his plan to establish a Hellenistic theocratic monarchy in Rome, inspired by Ptolemaic rule. Caligula was the first to cast aside the veil obscuring the princeps' ambiguous position with the Senate, openly asserting his monarchy.

All this, however, only gave him a sinister reputation among the sources. Even when some ambiguous decisions can be explained—such as his war against Neptune—historians portray them in the same unfavourable light.

To better understand this perception, let's step back. Caligula's early popular fame stemmed from being the son of Germanicus, grandson of Tiberius, and avenger of the Teutoburg Forest. Germanicus died near Antioch in 19 AD, when Caligula was a child, amid suspicions of poisoning by his uncle. He was also the grandson of Drusus the Elder, who brought Roman rule to the Elbe. In the name of his father, grandfather, and his own ambition, Caligula launched new campaigns in Germany and Britain.

Caligula's military operations began in 39 AD and are described by sources, especially Suetonius, in almost Fantozzian tones: the princeps reportedly enjoyed staging mock pursuits of enemies or appearing cowardly before actual ones. However, evidence shows that Caligula and his lieutenants, including the future emperor Galba, repelled several Chatti and Suevi incursions into Gaul.

The British issue was different. After ordering a fleet built and supplies and war machines gathered near the English Channel, Caligula ordered his troops to strike the sea and collect shells as spoils for Neptune. He then claimed the submission of the British nobleman Adminus as his own victory and returned to Rome for his triumph.

Beyond the laughable scene, it is assumed that Caligula's action was nothing more than a coastal reconnaissance and diplomacy operation: the shells the soldiers collected may have been a metaphor. Ancient sources sometimes interpreted shells as symbols of female genitals, possibly referencing local brothels, or as figurative references to British boats landing on the shore. As for Adminius's surrender, although modest and amplified by the princeps, it demonstrates that Rome had by now entered the affairs of the British tribes. It is no coincidence that a few years later, Claudius would begin the conquest of the island.