The Twelve Caesars, often titled Lives of the Caesars in English, is a collection of 12 biographies covering Julius Caesar and the first 11 emperors of the Roman Empire in historical order. It was written in 121 CE by Suetonius. The Twelve Caesars is, along with Tacitus’s Histories and the Annals and Cassius Dio’s History of Rome, one of the earliest sources that has a narrative covering political events in the Roman Empire from about the mid-first century BCE to 96 CE, which covers the fall of the Roman Republic through to the end of Rome’s second imperial dynasty, the Flavians. The work is mostly complete, although it appears the beginning of the biography of Julius Caesar was lost. This guide refers to Catharine Edwards’s translation from Oxford University Press, which was published under the title The Lives of the Caesars.

Historians still debate how reliable The Twelve Caesars is. This is partly because Suetonius clearly has a bias as a member of the Roman aristocracy. As someone working for Trajan and Hadrian, he likely had a political motive in making the emperor Domitian (reigned 81-96 CE) look bad. After all, it was Domitian’s assassination that paved the way for Trajan to become emperor, and Hadrian was Trajan’s chosen successor and relative by marriage. Also, The Twelve Caesars is well-known for its lurid, gossipy content, suggesting that Suetonius was not too careful in considering the biases of his sources or the plausibility of certain stories. Finally, it should be noted that Suetonius only lived through the lives of the last five emperors he described; the first subject of The Twelve Caesars, Julius Caesar, died just under a century before he was born. Nonetheless, as someone who worked in the imperial archives, Suetonius would have had complete access to a wealth of first-hand materials, like letters, memoirs, wills, political decrees, and so on, dating back to the time of Julius Caesar, and he often cites such sources. Also, many of Suetonius’s key claims are corroborated by other historical sources. Because of this, historians of ancient Rome usually agree that Suetonius is reliable overall but should be read with a critical eye.

Rather than being a straightforward historical narrative like the works of Tacitus or Cassius Dio, The Twelve Caesars is organized as a group of separate biographies. Even though Julius Caesar was never emperor, it is titled The Twelve Caesars or Lives of the Caesars because the first emperors of the Julio-Claudian dynasty were his extended family by blood, marriage, or adoption, so they used his surname or cognomen as Caesar. Later emperors who were not at all related to the Julio-Claudians continued using “Caesar” as one of their titles. Each biography is named after their subject. Chapters like “The Deified Julius Caesar” and “The Deified Augustus” are so named because very early on it became customary for the Senate to declare particularly well-favored emperors as gods after their deaths (hence Emperor Vespasian’s famous quip when he was dying, “Alas! I think I’m becoming a god” [The Deified Vespasian 23]).

Each biography begins with a description of its subject’s family background and childhood with the exception of “The Deified Julius Caesar.” They continue with an account of their personal appearance and characteristics and the Caesar’s actions, and conclude with an account of their death. While the biographies begin and end with the Caesar’s birth and death, they tend to be organized more by topic than by chronology, as one might expect from a modern biography.

“The Deified Julius Caesar” begins with Suetonius discussing Julius Caesar’s political and military career. Later, he is elected consul and aligns himself to two of the most powerful men in Rome, Gnaeus Pompey and Marcus Crassus. When his consulship ended, Caesar had himself appointed the governor of the frontier province Transalpine Gaul and left Rome to elude his political enemies. Suetonius then describes Caesar’s invasion of Gaul, which was immediately followed by a civil war between Caesar and Pompey after their alliance broke down. After recounting Caesar’s victory over Pompey and his enemies in the Senate, Suetonius discusses Caesar’s eccentric personal life, his physical appearance, his qualities as a general and a friend, and the reforms he enacted when he was made dictator for life. Finally, Suetonius concludes with a description of the conspiracy against Julius Caesar and his resulting assassination.

“The Deified Augustus” is the longest book because, naturally, it describes the longest-reigning Caesar, Augustus, whose original name was Octavian. After impressing his great-uncle Julius Caesar with his characteristics, Caesar made Octavian his heir. Using Caesar’s fortune and political alliances with Mark Antony and Marcus Lepidus, Octavian took control of the Roman Empire, defeating Caesar’s enemies and then his former ally Mark Antony as well as Antony’s lover, Queen Cleopatra VII of Egypt, in war. The Senate gave Octavian the name Augustus after the fall of Mark Antony, and he assumed various political powers, becoming the de facto ruler of the Roman Empire and its first emperor while still leaving the republican institutions of Rome largely intact. Augustus used his powers to improve the city of Rome. Particularly, Suetonius stresses Augustus as a reformer who streamlined the government and tried to impose moral change. Suetonius also presents Augustus as a leader who, despite his power, avoided being perceived as a monarch. Finally, Suetonius discusses Augustus’s widely mourned death.

Suetonius begins “Tiberius” with a lengthy discussion of Tiberius’s family, the Claudii, an ancient Roman aristocratic family. Tiberius was the son of a man who fell on the wrong side of the civil wars and so began his life as a fugitive. However, Tiberius’s fortunes changed when his mother Livia divorced his father and married Augustus. Tiberius went on to have a promising military career and was forced to divorce his wife Vipsania so he could marry Augustus’s widowed daughter Julia. Suetonius implies that Augustus reluctantly had Tiberius succeed him to the imperial office because no one was suitable. As emperor Tiberius was conservative, reluctant to act against critics, and modest. However, his behavior changed when he left Rome and stayed on the island of Capri, where he reveled in who he truly was and engaged in decadent sexual behavior while becoming more brutal and tyrannical. In fact, Suetonius writes that Tiberius, under the influence of Sejanus, the head of the praetorian guard, began to arrest and execute the sons of Augustus’s granddaughter, Agrippina the Elder, even after Tiberius turned against Sejanus. According to Suetonius, Tiberius died hating himself and despised by the people. He left the imperial office to Agrippina’s only surviving son, Gaius “Caligula.”

Suetonius begins “Caligula” by talking about Gaius Caligula’s father, Germanicus, who was Tiberius’s nephew and extremely popular with the public. Suetonius describes Caligula as a young man who fawned over those in power but acted cruelly to everyone else. Still, when he became emperor Caligula was jubilantly received, since Tiberius was so hated and Germanicus was so loved. Suetonius discusses several public games and new buildings Caligula funded before describing the ways in which Caligula was a “monster” (“Caligula,” Section 22). Suetonius reports that Caligula ruthlessly persecuted members of the Senate, committed incest with his sisters, and believed he was a god. This alleged reign of terror ended when Caligula, his wife Caesonia, and his daughter Drusilla were killed by assassins led by a member of the praetorian guard.

In “The Deified Claudius,” Suetonius emphasizes a physical disability Claudius was born with, which made him an embarrassment to the imperial family. Denied any military or political responsibilities even though he was the nephew of Tiberius and great-nephew of Augustus, Claudius devoted himself to scholarly work, especially history. It was not until the reign of Caligula that Claudius was granted any political offices. Still, according to an anecdote cited by Suetonius, in the aftermath of the assassinations of Caligula and his family, a soldier found Claudius cowering behind a curtain and the praetorian guard proclaimed him emperor on the spot. Claudius was a scrupulous ruler interested in public works like Rome’s grain supply and hearing judicial cases personally, but he was cowardly and unreliable when it came to legal judgments. Suetonius downplays Claudius’s conquest of Britain, even though it was the most significant expansion of Roman territory since Julius Caesar’s invasion of Gaul. After his wife Messalina was executed, Claudius married his own niece, Agrippina the Younger, and favored Agrippina’s son Nero as his successor over his own son, Britannicus. When Agrippina suspected that Claudius was about to turn on her, Suetonius alleges that she poisoned Claudius, paving the way for Nero to become emperor.

“Nero” describes Nero’s paternal family, the Domitians, who were aristocrats with a long history and a poor reputation. After the death of Claudius, Nero became emperor at the age of 17 and vowed to reign in a more open, less corrupt way than his predecessors. While Nero carried out some reforms, he was more interested in public games and theatrical and musical performances. Suetonius alleges that Nero was obsessed with luxuries and sex, and he committed violence against his own family, killing his stepbrother and cousin Britannicus and even having his own mother assassinated because she annoyed him. The military eventually rebelled against Nero. After being deserted by his own guards and condemned by the Senate, he committed suicide.

With “Galba,” Suetonius depicts the first Roman emperor from outside the Julio-Claudian dynasty. While Galba was not related to the Julio-Claudians, he had a distinguished background and close ties to Augustus’s wife Livia and to Claudius. While governor of the province of Africa, Galba joined the military revolt against Nero. However, his harsh treatment of his soldiers and attempts to force aristocrats who received gifts from Nero to return most of them made him unpopular. Galba was slain by his own soldiers just as his political rivals started a civil war.

“Otho” describes how Otho came from Etruscan aristocracy and rose to prominence as a courtier in Nero’s imperial court. When Nero turned against Otho, Otho backed Galba. When Galba reneged on a promise to name Otho his heir, Otho tried to seize the imperial office himself. His efforts were in vain, however, and he killed himself before he could be defeated on the battlefield and captured.

When describing Vitellius’s background in “Vitellius,” Suetonius claims he could not verify whether Vitellius was from an aristocratic background or descended from a freedman or a cobbler. Whatever his family origins, Vitellius achieved wealth and influence as a part of the imperial court under Caligula, Claudius, and Nero. After Galba’s assassination, Vitellius decided to challenge Otho for the imperial office, and the superiority of his army drove Otho to suicide. Vitellius was cruel and gluttonous, dedicating himself to endless expensive banquets. After a reign of eight months, much of the military defected from Otho to the general Vespasian, whose forces captured Rome and then caught and killed Vitellius.

“The Deified Vespasian” explains how the emperor Vespasian ended a period of civil war and became the first emperor since the Julio-Claudians to establish a stable dynasty. Vespasian was also the first emperor to not come from an aristocratic background, but from a family of tax collectors and mid-ranking military officials. He rose through the ranks in the military and came out of the civil war following Nero’s death as emperor. As emperor, Vespasian was merciful toward his enemies and was hardworking and generous. According to rumor, he was greedy and raised money in unconventional ways, but Suetonius argues that he spent tax revenue well and had to replenish the treasury that was depleted by Nero and the civil war. When he was dying, Vespasian ensured that the Senate would allow his son Titus to succeed him as emperor, beginning the Flavian dynasty.

“The Deified Titus” details Titus’s wide popularity, though he was widely criticized before he became emperor for heavy drinking, for his affair with the Jewish queen Berenice, and for his alleged cruelty. Once he became emperor, however, he ended his relationship with Berenice. Suetonius claims he refused to act violently against people who plotted against him and was exceptionally generous to survivors of the Mt. Vesuvius eruption. However, Titus died from an illness after a reign of only two years.

The last book in The Twelve Caesars is “Domitian,” which covers the third and last emperor in the Flavian dynasty, Titus’s brother Domitian. Domitian was kind and charitable in his early years but grew more vicious later in life. As emperor, Domitian became something of a megalomaniac, demanding the Senate refer to him as “master and god” (Domitian 14), and he had many senators murdered. Domitian was assassinated by his wife’s steward. Suetonius concludes the biography by claiming that Domitian had a prophetic dream that the empire would be prosperous and happy in the years after his death.