Sejanus Lucius Aelius Seianus ( 20 BCE – October 18 , CE 31 ) , commonly known as Sejanus , was an ambitious soldier , friend and confidant of the Roman Emperor Tiberius . An equestrian by birth , Sejanus rose to power as prefect of the Roman imperial bodyguard , known as the Praetorian Guard , of which he was commander from CE 14 until his death in CE 31 . While the Praetorian Guard was formally established under Emperor Augustus , Sejanus introduced a number of reforms which saw the unit evolve beyond a mere bodyguard into a powerful and influential branch of the government involved in public security , civil administration , and ultimately political intercession ; changes which would have a lasting impact on the course of the Principate . During the 20s , Sejanus gradually accumulated power by consolidating his influence over Tiberius and eliminating potential political opponents , including the emperor ' s son , Drusus Julius Caesar . When Tiberius withdrew to Capri in 26 , Sejanus was left in control of the entire state mechanism as " de facto " ruler of the empire . For a time the most influential and feared citizen of Rome , Sejanus suddenly fell from power in 31 , the year his career culminated with the consulship . Amidst suspicions of conspiracy against Tiberius , Sejanus was arrested and executed , along with his followers . Family . Sejanus was born in 20 BCE at Volsinii , Etruria , to the family of Lucius Seius Strabo . The Seii were Romans of the equestrian class ( or knights ) , the lower of the two upper social classes of the Roman Republic and the early Roman Empire . Sejanus ' grandfather however maintained relations with senatorial families through his marriage with Terentia , a sister of the wife of Gaius Maecenas , who was one of Emperor Augustus ' most powerful political allies . Strabo himself married into equally illustrious families . He may have married a daughter of Quintus Aelius Tubero , allying himself with the more prestigious Aelian gens . Lucius Seius Tubero , who became suffect consul in 18 , was probably his son . Strabo ' s last wife was Cosconia Gallita , sister of Servius Cornelius Lentulus Maluginensis ( suffect consul in 10 ) and Publius Cornelius Lentulus Scipio ( suffect consul in 2 ) , and perhaps half - sister of Quintus Junius Blaesus ( suffect consul in 10 ) . Sejanus could have been a child of this marriage . He was later adopted into the Aelian gens by Gaius Aelius Gallus , and by Roman custom became known as Lucius Aelius Seianus , or simply Sejanus . The adoptive family of Sejanus counted two consuls among their family : the aforementioned Quintus Aelius Tubero ( consul in 11 BCE ) , and Sextus Aelius Catus ( consul in 4 ) , who was the father of Aelia Paetina , the second wife of the Emperor Claudius . Sejanus ' uncle Junius Blaesus distinguished himself as a military commander who became proconsul of Africa in 21 , and earned triumphal honors by crushing the rebellion of Tacfarinas . According to the ancient historian Tacitus , Sejanus was also a former favourite of the wealthy Marcus Gavius Apicius , whose daughter may have been Sejanus ' first wife Apicata . With Apicata , he had three children , two sons and one daughter : Strabo , Capito Aelianus and Junilla . Rise to power . Praetorian prefect . It is likely that Sejanus ' father Strabo came to the attention of Augustus through his father ' s connection with Maecenas . Sometime after 2 BCE , Strabo was appointed prefect of the Praetorian Guard , one of the two most powerful positions a Roman knight could attain in the Empire . This office he carried on dutifully and without incident until the death of Augustus in 14 . Little is known about the life Sejanus led prior to this date , but according to Tacitus , he accompanied Gaius Caesar , adopted grandson of Augustus , during his campaigns in Armenia in 1 BC . It was upon the accession of Tiberius in 14 , that Sejanus was appointed prefect of the Praetorian Guard as the colleague of his father Strabo , and began his rise to prominence . The Praetorian Guard was an elite unit of the Roman army formed by Augustus in 27 BC , with the specific function to serve as a bodyguard to the emperor and members of the imperial family . Much more than a guard however , the Praetorians also managed the day - to - day care of the city , such as general security and civil administration . Furthermore , their presence served as a constant reminder to the people and the Senate of the substantial armed force which served as the basis for the imperial power . Augustus was careful however to uphold the republican veneer of this regime , and only allowed nine cohorts to be formed ( one fewer than in a normal Roman legion ) , which were inconspicuously scattered across various lodging houses in the city , and commanded by two prefects . When Strabo was assigned to the governorship of Egypt in 15 , Sejanus became the sole commander of the Praetorians and instigated reforms that helped shape the guard into a powerful tool of the principate . In 20 the scattered encampments inside the city were centralized into a single garrison just outside Rome and the number of cohorts was increased from nine to twelve , one of which now held the daily guard at the palace . The practice of joint leadership between two prefects was abandoned , and Sejanus himself appointed the centurion s and tribunes . With these changes in effect , Sejanus now commanded the complete loyalty of a force of around 12 , 000 soldiers , all of which were at his immediate disposal . The facade of Augustus was no longer maintained , and Tiberius openly displayed the strength of the guard at parades . Feud with Drusus . In his capacity of Praetorian prefect Sejanus quickly became a trusted advisor to Tiberius . By 23 he already exerted a considerable influence over the decisions of the emperor , who referred to Sejanus as " Socius Laborum " ( my partner in my toils ) . By this time he had been raised to the rank of praetor , a position which was not normally granted to Romans of the equestrian class . A statue had been erected in his honor in the Theatre of Pompey , and in the Senate his followers were advanced with public offices and governorships . However this privileged position caused resentment among the senatorial class and the imperial family , in particular earning him the enmity of Drusus Julius Caesar , Tiberius ' son . The history of Sejanus and Drusus dated back to at least 15 AD . That year a mutiny had broken out among legions posted in Pannonia and Germania . While his adopted son Germanicus restored order in Germania , Tiberius ' biological son Drusus was sent to quell the uprising in Pannonia , accompanied by Sejanus and two Praetorian cohorts . In part due to what the soldiers believed to be bad omen s , Drusus quickly managed to restore the stability in the army and publicly put the chief instigators to death . The camp was purged of mutineers by the Praetorians and the legions returned to the winter barracks . Despite this success , the following years witnessed a growing animosity between Drusus and Sejanus . Since the accession of Tiberius , Drusus had been systematically groomed as the successor of his father , successfully commanding legions in Illyricum in 18 , and sharing the consulship with Tiberius in 21 . In practice however it was still Sejanus who was the second man in the empire , and he was ambitious to further expand his power . As early as 20 , Sejanus had sought to solidify his connection with the imperial family by betrothing his daughter Junilla to the son of Claudius , Claudius Drusus . At the time the girl was only 4 years old but the marriage was nonetheless prevented when the boy accidentally died a few days later of asphyxia tion . When this failed it seems Sejanus turned his attention toward eliminating Drusus . By 23 the enmity between the two men had reached a critical point . During an argument Drusus had struck the prefect with his fist , and he openly lamented that " a stranger was invited to assist in the government while the emperor ' s son was alive " . With Tiberius already in his sixties , there was a real possibility of Drusus succeeding his father in the near future . To secure his own position Sejanus secretly plotted against Drusus and succeeded in seducing his wife Livilla . With her as an accomplice Drusus was slowly poisoned and died of seemingly natural causes on September 13 , 23 . Consolidation of power . The loss of his son was a major blow to Tiberius , both personally and politically . Over the years he had grown increasingly disillusioned with the position of princeps , and by sharing the tribunician powers with Drusus in 22 had prepared to relent some of his responsibilities in favour of his son . With these hopes now dashed , Tiberius left his administration more than ever in the care of Sejanus , and looked toward the sons of Germanicus ( Nero Caesar , Drusus Caesar , and Caligula ) as possible future heirs . Germanicus himself had died in 19 in somewhat suspicious circumstances in Syria . Following his death , his wife Agrippina the Elder returned to Rome with their six children and became increasingly involved with a group of senators who opposed the growing power of Sejanus . Her relations with Tiberius became increasingly fraught as she made it clear that she believed that he was responsible for the death of Germanicus . The climate was further poisoned by the hatred that Tiberius ' mother Livia Drusilla felt for her , since Agrippina ' s ambition , to be the mother of emperors and thus Rome ' s first woman , was an open secret . To Sejanus personally , Agrippina ' s sons Nero Caesar , Drusus Caesar and Caligula were considered a direct threat to his power . Meanwhile , Sejanus again attempted to marry into the Julio - Claudian family . Having divorced Apicata two years earlier he requested marriage with Livilla in 25 , possibly with an eye towards placing himself , as an adopted Julian , in the position of a potential successor . The emperor denied this request , warning Sejanus that he was in danger of overstepping his rank . Alarmed by this sudden denigration , Sejanus changed his plans and began to isolate Tiberius from Rome . By fueling his paranoia towards Agrippina and the Senate he induced the emperor to withdraw to the countryside of Campania , which he did in 26 , and finally to the island of Capri , where he would spend the remainder of his life until his death in 37 . Guarded by the Praetorians , Sejanus easily controlled all information that passed between Tiberius and the capital . Despite the withdrawal of Tiberius from Rome ' s political scene , the presence of Livia seems to have checked Sejanus ' overt power for a time . According to Tacitus , her death in 29 changed all that . Sejanus began a series of purge trials of senator s and wealthy equestrians in the city , removing those capable of opposing his power as well as extending the imperial ( and his own ) treasury . Networks of spies and informers brought the victims to trial with false accusations of treason , and many chose suicide over the disgrace of being condemned and executed . Among those who perished were Gaius Asinius Gallus , a prominent senator and opponent of Tiberius who was linked to Agrippina ' s faction . Agrippina herself and two of her sons , Nero and Drusus were arrested and exiled in 30 , and later to death in suspicious circumstances . Only Caligula , as the last remaining son of Germanicus , managed to survive the purges of Sejanus , and that he did by moving to Capri with Tiberius in 31 . Downfall . Denunciation . In 31 , despite his equestrian rank , Sejanus shared the consulship with Tiberius " in absentia " , and finally became betrothed to Livilla . Tiberius had not been seen in Rome since 26 . Sejanus was de facto ruler of the Roman Empire , and senators and equestrians openly courted his favour as if he were such . His birthday was publicly observed and statues were being erected in his honour . With most of the political opposition crushed , Sejanus felt his position was unassailable . As the ancient historian Cassius Dio describes : Sejanus was so great a person by reason both of his excessive haughtiness and of his vast power , that , to put it briefly , he himself seemed to be the emperor and Tiberius a kind of island potentate , inasmuch as the latter spent his time on the island of Capreae . Through years of crafty intrigues and indispensable service to the emperor , Sejanus had worked himself up to become the most powerful man in the Empire . By the end of 31 , he would be arrested , summarily executed and his body unceremoniously cast down the Gemonian stairs . Exactly what caused his sudden downfall is unclear : ancient historians disagree about the nature of his conspiracy , whether it was Tiberius or Sejanus who struck first , and in which order subsequent events transpired . Modern historians consider it unlikely that Sejanus plotted to seize the imperial power for himself and , if he had planned so at all , rather might have aimed at overthrowing Tiberius to serve as a regent to Tiberius Gemellus , son of Drusus , or possibly even Gaius Caligula . Unfortunately the relevant section pertaining to this period in the " Annals " of Tacitus has been lost . According to Josephus however , it was Antonia , the mother of Livilla , who finally alerted Tiberius to the growing threat Sejanus posed ( possibly with information provided by Satrius Secundus ) , in a letter she dispatched to Capri in the care of her freedman Pallas . According to Juvenal , a letter was sent from Capri with the orders to execute Sejanus without a trial . Further details concerning Sejanus ' fall are provided by Cassius Dio , writing nearly 200 years after the facts in his " Roman History " . It appears that , when Tiberius heard to what extent Sejanus had already usurped his authority in Rome , he immediately took steps to remove him from power . However , he realised that an outright condemnation could provoke Sejanus to attempt a coup . Instead , Tiberius addressed a number of contradictory letters to the Senate , some of which praised Sejanus and his friends , and some of which denounced them . Tiberius variously announced that he would arrive in Rome the next day or that he was at the point of death . He stepped down as consul , forcing Sejanus to do the same , and conferred an honorary priesthood upon Caligula , rekindling popular support for the house of Germanicus . The ensuing confusion was successful in alienating Sejanus from many of his followers . With the intentions of the emperor no longer clear , it was now deemed a safer course of action at Rome to withdraw from overt support to Sejanus until the matter was clearly settled . When it became clear to Tiberius that support for Sejanus was not as strong as the emperor had feared , his next step was to choose Naevius Sutorius Macro , previously prefect of the vigiles ( Roman police and fire department ) , to replace Sejanus and effect his downfall . On October 18 , 31 , Sejanus was summoned to a Senate meeting by a letter from Tiberius , ostensibly to bestow the tribunician powers upon him . At dawn he entered the Senate , but while the letter was being read Macro assumed control of the Praetorian Guard , and members of the vigiles led by Graecinius Laco surrounded the building . The senators at first congratulated Sejanus , but when the letter , which first digressed into completely unrelated matters , suddenly denounced him and ordered his arrest , he was immediately surrounded and escorted to prison . Execution and aftermath . That same evening , the Senate convened at the Temple of Concord and summarily condemned Sejanus to death . He was led from prison and strangled . His body was cast onto the Gemonian stairs , where the crowd tore it to pieces . Riots ensued in which mobs hunted down and killed anyone they could link to the regime of Sejanus . The Praetorians also resorted to looting when they were accused of having conspired with the former prefect . Following the issue of " damnatio memoriae " by the Senate , his statues were torn down and his name obliterated from all public records . On October 24 , Sejanus ' eldest son Strabo was arrested and executed . Upon learning of his death , Apicata committed suicide ( October 26 ) after addressing a letter to Tiberius claiming that Drusus had been poisoned with the complicity of Livilla . The accusations were further corroborated by confessions from Livilla ' s slaves , who admitted to having administered the poison to Drusus . Enraged upon learning the truth , Tiberius soon ordered more executions . Livilla herself committed suicide or , as legend would have it , was forcibly starved to death by her own mother Antonia Minor . The remaining children of Sejanus , Capito Aelianus and Junilla , were executed in December of that year . According to ancient historians , because there was no precedent for the capital punishment of a virgin , Junilla was raped before her execution , with the rope around her neck . Their bodies were likewise thrown down the Gemonian stairs . At the beginning of the following year , " damnatio memoriae " was passed on Livilla . Although Rome at first rejoiced at the demise of Sejanus , the city quickly plunged into more extensive trials , as Tiberius relentlessly persecuted all those who could in any way be tied to the schemes of Sejanus or had courted his friendship . The Senatorial ranks were purged ; the hardest hit were those families with political ties to the Julians . Even the imperial magistracy was not exempted from Tiberius ' wrath . Arrests and executions were now supervised by Naevius Sutorius Macro . The political turmoil would continue until the death of Tiberius in 37 , after which he was succeeded by Caligula . Most historical documentation of Tiberius ' revenge is given from Suetonius and Tacitus . However their portrayal of a tyrannical , vengeful emperor has been challenged by several modern historians . The prominent ancient historian Edward Togo Salmon notes in his work , " A history of the Roman world from 30 B . C . to A . D . 138 " : Legacy . Praetorian Guard . The reforms of Sejanus , most significantly the founding of the Castra Praetoria , essentially established the Praetorian Guard as the powerful political force for which it is primarily known today . Henceforth the entire Guard was at the disposal of the emperors , but the rulers were now equally at the mercy of the Praetorians . The reality of this was seen in 31 when Tiberius was forced to rely upon the vigiles against the soldiers of his own guard . Although the Praetorian Guard proved faithful to the aging Tiberius , their potential political power had been made clear . The power Sejanus attained in his capacity as prefect proved Maecenas right in his prediction to Augustus that it was dangerous to allow one man to command the guard . Cassius Dio notes that after Sejanus , no other prefect except Gaius Fulvius Plautianus , who commanded the Guard under Septimius Severus , would rise to such influence . Nevertheless , following his death the Guard began to play an increasingly ambitious and bloody role in the Empire . With the right amount of money , or at will , they assassinated emperors , bullied their own prefects , or turned on the people of Rome . In 41 Caligula was killed by conspirators from the senatorial class and from the Guard . The Praetorians placed Claudius on the throne , daring the Senate to oppose their decision . In the late 1st century , a calculated uprising of Praetorians against Emperor Nerva , led by Casperius Aelianus , forced Nerva to adopt the more popular Trajan as his son and successor . While it is unproven Sejanus ever did intend to overthrow and replace Tiberius , later prefects of the Guard did aspire to become emperor themselves . Upon the suicide of Emperor Nero in 68 , the Guard prefect Gaius Nymphidius Sabinus attempted to have himself declared emperor , on the pretence that he was the illegitimate son of Caligula . The attempt failed and Sabinus was killed by his own soldiers . In the early 3rd century , Plautianus was executed after a failed conspiracy against Septimius Severus . According to sources , the downfall of Plautianus was largely due to suspicion of Severus ' son Caracalla , who was himself later murdered and replaced by his Praetorian prefect Marcus Opellius Macrinus . Historiography . With the exception of Velleius Paterculus , ancient historians have universally condemned Sejanus , although accounts differ to which extent Sejanus was manipulated by Tiberius or the other way around . Suetonius Tranquillus asserts that Sejanus was merely an instrument of Tiberius to hasten the downfall of Germanicus and his family , and that he was quickly disposed of once he ceased to be useful . Tacitus , on the other hand , attributes much of the decline of Tiberius ' rule after 23 to the corrupting influence of Sejanus , although he is generally also harsh on Tiberius himself . Among the writers of the time who fell victim to the regime of Sejanus and its aftermath were the historians Aulus Cremutius Cordus , Velleius Paterculus and the poet Phaedrus . Cordus was brought to trial in 25 by Sejanus under accusations of treason . He was charged for having eulogized Marcus Junius Brutus and spoken of Gaius Cassius Longinus as the last of the true Romans , which was considered an offence under the " Lex Maiestas " , and the Senate ordered the burning of his writings . His fall is elaborated upon by Seneca the Younger , in his letter to Cordus ' daughter Marcia " To Marcia , On Consolation " . Seneca however tells us that her father most likely incurred Sejanus ' displeasure for criticising him , because he had commissioned a statue of himself . We also know from this source that Cordus starved himself to death . Marcia was instrumental in saving her father ' s work , so that it could be published again under Caligula . Phaedrus was suspected of having alluded to Sejanus in his " Fables " , and received some unknown punishment short of death ( Cf . Fables I . 1 , I . 2 . 24 , and I . 17 ) . Velleius Paterculus was a historian and contemporary of Sejanus whose two - volume " The Roman History " details a history of Rome from the fall of Troy until the death of Livia Augusta in 29 . In his work he praises both Tiberius and Sejanus , even defending the latter ' s high position in the government despite his equestrian rank . How much of Paterculus ' writing is due to genuine admiration , prudence or fear remains an open question , but it has been conjectured that he was put to death as a friend of Sejanus . Literary interpretations . Sejanus ' fall is depicted in the section in Juvenal ' s Satire X on the emptiness of power . This reviews the destruction of his statues after the " damnatio memoriae " judgment and reflects on the fickleness of public opinion . The dramatist Ben Jonson borrowed from the poem for some passages in his " " . The play is seen as a topical reference to the fall of the former royal favourite , Robert Devereux , 2nd Earl of Essex , executed for treason two years before . Sejanus is also a leading figure in another Roman history play of about this time , the anonymous " Tragedy of Claudius Tiberius Nero " ( 1607 ) . Making political points through the use of this episode of Classical history was no new thing . In 16th century France the fall of the powerful Cardinal Mazarin was celebrated in a political pamphlet that also drew parallels with the career of Sejanus , " L ' Ambitieux ou le portraict d ' Aelius Sejanus en la personne du Cardinal Mazarin " ( Paris , 1542 ) . In England other royal favourites were to be seen in these terms . George Villiers , 1st Duke of Buckingham , is the target of an anonymous manuscript Roman tragedy , " The Emperor ’ s Favourite " . The prudent need for anonymity is suggested by the arrest of Sir John Eliot , who was sent to the Tower of London for his outspoken criticism of the Duke in the 1626 parliament , comparing him to Sejanus . Following Buckingham ’ s death in 1628 , when it was safer to do so , a translation of a history by Pierre Matthieu was published under the title , " The Powerful Favourite , the life of Aelius Sejanus " . This was followed in 1634 by another translation , Sir Thomas Hawkins ’ " Politicall Observations upon the Fall of Sejanus " , which had originally been titled " Della peripetia di fortuna " ( Of Changes of Fortune ) by its author , Giovanni Battista Manzini . Later in the century Anthony Ashley Cooper , 1st Earl of Shaftesbury , was the target of the four - page political pamphlet " Sejanus , or The popular favourite , now in his solitude , and sufferings " , signed with the pseudonym Timothy Tory . ( 1681 ) . Referring to the Earl ’ s imprisonment in the Tower on a charge of treason , in this case the story of Sejanus is being interpreted as an argument for Absolute monarchy , direct rule without the intermediary of politicians . The name of Sejanus continued to be pressed into political service during the 18th century . The Prime Minister Robert Walpole was attacked in 1735 in the course of a popular skit , " C - - - - - and country : A play of seven acts . . . the whole concluding with the grand masque , call ' d , The downfall of Sejanus . " Its authorship is attributed to ' a masquerader ' and in the printed version the masque precedes the play , although it is performed last . This gives the clue of how to take what is to follow and consists of a conversation between Punch and the Hangman , opening with the question ' Is this same Sejanus to go out of the World like a Man , or to die the Death of a mad Dog ? For he has lived like a sad One , from the first Day that the Emperor Tiberius took him into Favour . ' A subtler attack on a later prime minister occurred in 1769 when Jonson ' s " Sejanus " was reissued under the title of " The Favourite " . This was prefaced with a tongue in cheek dedication to Lord Bute , denying that there can be any comparison between the conduct of Sejanus and that of his lordship . Elsewhere in Europe , there were other dramatic adaptations of the story . They included Jean de Magnon ’ s rhyming tragedy , " Sejanus " ( 1647 ) and Henri van der Zande ' s " De dood van Elius Sejanus of Spiegel voor der vorsten gunstelingen " ( The death of Sejanus , a mirror for the favourites of princes , Amsterdam 1716 ) . Later in England , there was another recycling of Jonson ’ s tragedy by the Irish actor Francis Gentleman . Abridged and ‘ improved ’ by some additions of his own , he published his " Sejanus , a tragedy : as it was intended for the stage " ( 1752 ) when he could not get it acted . Later plays include a 5 - act tragedy by A . Arterton ( 1875 ) and the privately printed " Sejanus : A Tragedy in Five Acts " by P . J . A . Chaulk ( 1923 ) A later fictional treatment of the historical episode appeared as the first story of Edward Maturin ' s " Sejanus , and Other Roman Tales " ( New York 1839 ) . It also figures in Robert Graves ' " I , Claudius " ( 1934 ) . The novel was given new life when it was adapted as the TV series in 1976 ; in this Antonia sends the letter of accusation to Tiberius via Claudius after discovering her daughter is plotting with Sejanus . " The Caesars " ( 1968 ) was an earlier television series which featured Sejanus . The fact that Pontius Pilate was a nominee of Sejanus and implicated in the latter ’ s anti - Semitic policies has encouraged the inclusion of Sejanus in novels dealing with the circumstances of Jesus Christ ’ s crucifixion . The first of these was Miles Gerald Keon ’ s " Dion and the Sibyls : A Classic Christian Novel " , published in London in 1866 , and from the Catholic Publication Society in New York in 1872 . Later examples have included Paul L . Maier ' s " Pontius Pilate " ( Grand Rapids MI 1968 ) and Chris Seepe ' s " The Conspiracy to Assassinate Jesus Christ " ( Toronto 2012 ) . The aim of some later novels has been to concentrate as much on local colour as on the story . This was true of William Percival Crozier ' s historical romance " The Fates Are Laughing " ( 1945 ) , set during the fall of Sejanus and the reign of Caligula and written by a Classicist with an eye for detail . It is equally true of some recent detective novels set in Roman times . David Wishart ' s " Sejanus " ( London , 1998 ) , features Marcus Corvinus , and James Mace ' s " Empire Betrayed : Tribune Cursor and the Fall of Sejanus " ( 2013 ) a military colleague of Sejanus .