According to historian Philo of Alexandria, only months into his rule, young Emperor Gaius became ill with a terrible fever. The populace of Rome was driven to public mourning at the dark news of their beloved new emperor. After years of heavy taxes and harsh discipline under Tiberius, the young Gaius had been a breath of fresh air. As soon as he was named emperor, he freed many of Tiberius's captives accused of treason, gave bonuses to the military, and began reforms throughout the empire. He was friendly with his family, such as keeping his oaf uncle Claudius around him despite the man's clear deformities. Gaius even adopted his former co-heir and grandson of Tiberius, Gemellus, as his own son.
Shortly before his death, Gaius proclaimed his sister Drusilla (with whom there were horrid rumors of incest, but surely only rumors) as heir. When he succumbed to the fever, Drusilla herself announced to the people and proclaimed a week of mourning. Temples were closed, the Senate would not meet, and market days were canceled. During this time, Drusilla worked to secure her position. Rome had never had an empress or queen, and when the Senate reconvened, there would be much intrigue against her. Instead, she pushed political maneuvering so that she would step aside from direct rule (though inheriting great wealth), which would set up Gemellus as emperor. The grandson of Tiberius was much lauded, though few knew anything about him. He had been kept distant from the rest of the highly political family; his coming of age ceremony had not even been celebrated until he turned 18, four years after it should have. Gemellus was not much used to attention and fell on the support of many advisers. They pulled his attention in many different directions, and it was Drusilla who kept him most in power. Upon her death of fever, like her brother, in the spring of 38, Gemellus became something of a rubber stamp.
The weak emperor led a push from the Senate for a return to the Republic. Seneca, one of their leaders, conducted a plan where Gemellus cut back on the payment of soldiers while Senate bills began to grant bonuses. With the army's loyalty changed to the Senate, the senators began to strip his powers, breaking the rule of imperator into the many offices it had been before Julius and Augustus had collected them. Taxes notoriously increased to pay for the growing bureaucracy, causing people to wish again for the rule of the lost Gaius, which caused Gemellus to make a sudden push to retake power. The political maneuver failed, and Gemellus was stripped of his final title, the family name Caesar, and made senator in a bill to reestablish rule by many.
With its focus of power upon internal affairs, the empire began to disintegrate. Britons remained independent when many in Rome felt a single campaign could take hold of the whole island. Conquered German barbarians from the north declared an end to their tribute, and the Senate debated the issue to death. War in the east allowed the Parthians to march into Roman Syria, which finally spurred action from the General Titus, son of General Vespasian who had helped defend the border from Briton raids. After years of fighting, Titus made great demands on the Roman coffers if he were to win this war, and the Senate instead opted to sue for peace. Armenia was granted to the Parthians, and Titus set about building forts in the east to protect Asia Minor as well as the Judaeans, who had held close to Rome in fear of Parthian invasion. Over the next few generations, the Jews would rebel as well, winning their freedom and reestablishing Judaean kings.
Rome would decline, breaking off piecemeal as a province became unprofitable with defense outgrowing taxes and income. Germans expanded through Europe, as did the Huns, and later Arabs arising from the Middle East. When the German horde began to encroach into Italy itself, the Romans turned back to their old system of dictators in time of troubles, electing the famous Constantine to defend the city. Constantine would manage to secure the oldest provinces, but much of the rest of the empire had already fallen. Instead, he consolidated and fortified Italy, which would remain a united force through the Middle Ages. Because of his fanatical support of Christianity, it would be dubbed the “Holy Roman Empire.”
In reality, Caligula survived his illness. His reign would be listed among the cruelest in human history with him openly mocking the Senate, torturing innocent citizens, and performing unbelievable acts of violence toward his own family. His evil would be balanced with generous festivals and keeping the army well paid, thus loyal. Finally conspiracies would form against him, succeeding as Cassius Chaerea of the Praetorian Guard stabbed Caligula for too many insulting nicknames. In the chaos, the soldiers would elect Claudius, who would prove a competent ruler and secure the rule of emperor in Rome for centuries.