AD 23

AD 23 (XXIII) was a common year in the Julian calendar during the reign of Roman Emperor Tiberius, notable for the death of his son and designated successor Drusus Julius Caesar on 13 September, widely attributed by ancient historians to poisoning orchestrated by Praetorian prefect Lucius Aelius Sejanus in collaboration with Drusus's wife, Livia Julia (Livilla).^[1]^[2] This intrigue marked a pivotal consolidation of Sejanus's power, eliminating a key rival and shifting dynastic prospects toward Germanicus's line before further purges.^[3] The year also saw Sejanus direct the construction of the Castra Praetoria, a fortified permanent camp for the Praetorian cohorts on Rome's northeastern outskirts, centralizing imperial security forces previously dispersed across the city.^[4]^[5] It was the year of the consulship of Gaius Asinius Pollio and Gaius Antistius Vetus.^[6] In the client kingdom of Mauretania, King Juba II died, passing rule to his son Ptolemy under continued Roman oversight.^[7]

Events

Roman Empire

In AD 23, Emperor Tiberius, who had ruled since AD 14, faced the sudden death of his son and designated heir, Drusus Julius Caesar, on September 14, potentially from poisoning administered by Lucius Aelius Sejanus, the prefect of the Praetorian Guard, with the complicity of Drusus's wife, Livilla.^[8] ^[9] This event, reported by ancient sources including Tacitus and Suetonius as a deliberate act to eliminate a rival, left Tiberius without an adult male successor from his direct line, intensifying intrigue around the Julio-Claudian succession and bolstering Sejanus's influence over imperial administration.^[10] Sejanus, leveraging his control over the guard, directed the construction of the Castra Praetoria, a fortified permanent camp for the 9,000-strong Praetorian Guard on Rome's northeastern outskirts, completed around this year to centralize and professionalize the emperor's elite forces. ^[11] The death further isolated Tiberius, who increasingly withdrew from public life amid suspicions of court conspiracies, delegating more authority to Sejanus while residing on the Palatine Hill.^[12] In the empire's client states, Juba II, king of Mauretania since circa 25 BC and a Roman-installed ruler noted for his loyalty and cultural patronage, died of natural causes; he had named his son Ptolemy as co-ruler in AD 21, ensuring a smooth transition under Roman oversight.^[13] No major military campaigns or provincial revolts were recorded for the year, reflecting a period of internal consolidation rather than expansion, with the empire's frontiers stable from the Rhine to the Euphrates.^[14]

China

In 23 AD, the Xin dynasty (AD 9–23), established by the regent-turned-usurper Wang Mang, collapsed under the weight of rebellions fueled by crop failures, economic disruptions from his land reforms and currency changes, and military overextension. Han loyalist factions, including the Lülin ("Green Forest") insurgents, capitalized on this unrest, launching coordinated uprisings across central and northern China. The decisive turning point came with the Battle of Kunyang in June–July, where Liu Xiu, a Han imperial clansman commanding roughly 9,000 Lülin troops, orchestrated a stunning defeat of a Xin force exceeding 400,000 under generals Wang Yi and Wang Xun; the victory stemmed from a bold cavalry sortie that exploited storm-induced panic and low morale among the besiegers.^[15]^[16] This improbable triumph fragmented Xin command structures and accelerated rebel advances toward the capital at Chang'an (modern Xi'an). By autumn, famine-stricken peasants joined the fray, overwhelming palace guards and storming the Weiyang Palace complex. On October 6, 23 AD, Wang Mang was captured and executed by the mob, his body reportedly dismembered and consumed in the chaos, marking the definitive end of his 14-year rule.^[17]^[18] The Xin downfall created a brief interregnum, with Liu Xuan—a collateral Han descendant—proclaimed Emperor Gengshi of Han later in 23 AD by Lülin leaders, signaling a nominal Han restoration amid ongoing civil strife. However, regional warlords and rival claimants, including Liu Xiu, vied for supremacy, delaying unified control until Liu Xiu's campaigns solidified the Eastern Han in AD 25.^[19]^[20]

Notable People

Births

Gaius Plinius Secundus, commonly known as Pliny the Elder, was born in AD 23 in Novum Comum (modern Como, Italy), within the Roman province of Gallia Transpadana.^[21] A prolific author, naturalist, philosopher, and military commander, Pliny served under emperors including Vespasian and Titus, rising to the rank of prefect of the fleet during the eruption of Mount Vesuvius in AD 79, which claimed his life while he investigated the event firsthand.^[22] His enduring legacy stems from Naturalis Historia, a 37-volume encyclopedia compiling knowledge on topics ranging from astronomy and geography to zoology and botany, drawing from over 2,000 sources and reflecting the breadth of Roman intellectual inquiry in the early imperial era.^[23] No other notable births from AD 23 are prominently recorded in surviving ancient sources, such as those from Tacitus or Suetonius, reflecting the selective preservation of elite Roman biographies over common individuals in this period.^[21]

Deaths

Drusus Julius Caesar, the son of Emperor Tiberius and designated heir to the Roman throne, died on 14 September AD 23 at the age of approximately 36. Ancient sources, including Tacitus in his Annals, attribute his sudden death to poisoning by Lucius Aelius Sejanus, the ambitious Praetorian prefect, who reportedly used a slow-acting toxin to mimic natural causes amid their escalating rivalry; Suetonius echoes suspicions of foul play linked to Sejanus' machinations against potential rivals.^[24] Drusus' passing left Tiberius without a direct successor, intensifying court intrigues and paving the way for Sejanus' temporary dominance. Juba II, King of Mauretania from c. 25 BC and a Roman client ruler educated in Rome under Augustus, died in AD 23 after a reign marked by cultural patronage and loyalty to the empire.^[13] Born c. 48 BC as the son of Juba I of Numidia, he had governed Mauretania since receiving it from Augustus, fostering trade, exploration, and Hellenistic influences while maintaining Roman alliances; his death prompted his son Ptolemy to succeed him under continued Roman oversight.^[25] Juba was interred in the Royal Mausoleum of Mauretania near modern Tipasa, Algeria, alongside his wife Cleopatra Selene II, daughter of Mark Antony and Cleopatra VII.^[13] In China, Wang Mang, the usurping emperor of the short-lived Xin dynasty (AD 9–23), was killed on 6 October AD 23 during the peasant-led rebellion that restored the Han dynasty.^[17] His reforms, intended to revive ancient ideals through land redistribution and currency changes, had provoked widespread famine and unrest, culminating in his overthrow by forces loyal to Liu Xiu, who became Emperor Guangwu; Mang's corpse was reportedly dismembered and devoured by rebels in Luoyang.^[17] This event ended the Xin interregnum and marked a pivotal restoration of Han rule.