This military history of Rome during the short reign of Caligula (37–41 CE) analyses the Emperor’s campaigns and personal character through the evidence of contemporary writers such as Suetonius, Tacitus and Josephus. Although only 24 when he came to power, he proved a competent military strategist and despite the accusations of madness, cruelty and sexual perversion, managed to set the groundwork of Roman foreign policy for his successor Claudius.