Claudius

Proclaimed emperor by the Praetorian Guard after the assassination of his nephew Caligula in AD 41, Claudius reached power despite having been kept from public life for most of his first fifty years. He was born in 10 BC at Lugdunum (modern Lyon), the son of Drusus the Elder, stepson of Augustus, and Antonia Minor, daughter of Mark Antony and Augustus's sister Octavia. Through both parents he stood at the junction of the Julian and Claudian branches of the dynasty, yet a limp, a stammer, and other infirmities led his family to regard him as unfit for office. He devoted his early life to scholarship, writing histories of the Etruscans and Carthaginians, now lost, reportedly with encouragement from the historian Livy.

As emperor Claudius proved more capable than his reputation suggested. In 43 he ordered the invasion of Britain, the most significant addition to the empire since Augustus, and visited the island briefly to receive the surrender of Camulodunum. His administration expanded the role of freedmen secretaries in central government, extended Roman citizenship in the provinces, and admitted Gallic notables to the Senate. Major public works included new aqueducts for Rome, the draining of the Fucine Lake, and a deep-water harbor at Ostia to secure the grain supply.

His marriages shaped the dynasty's final phase. His third wife, Valeria Messalina, bore him a son, Britannicus, and a daughter, Octavia, but was executed in 48 after going through a marriage ceremony with another man. Claudius then married his niece Agrippina the Younger, a great-granddaughter of Augustus, a union that required a change in Roman law. In 50 he adopted her son Lucius Domitius Ahenobarbus, who took the name Nero and was advanced ahead of Britannicus in the succession, marrying Claudius's daughter Octavia in 53.

Claudius died in October 54, and ancient sources widely allege that Agrippina poisoned him to secure the throne for her son, though certainty is impossible. He was deified after death, the first emperor so honored since Augustus. Nero succeeded him at the age of sixteen, and Britannicus died within a few months of the accession.