Question: Name the 500 year-old-republic that Florentius was a praetorian prefect for. 

Passages:
Thaumastus (born c. 400) was a friend and uncle of Sidonius Apollinaris.  His brother, the elder Apollinaris was born around 405 and was the praetorian prefect of Gaul under Valentinian III between 425 and 455.  Thaumastus and his brother were both sons of another Apollinaris, praetorian prefect of Gaul before 409 and were friends with his successor Decimus Rusticus.  Thaumastus was associated with Tonantius Ferreolus in the impeachment of Arvandus.  He was the father of Eulalia, born in 425, married before 450 to Flavius Probus, Roman Senator. Florentius was a Roman praetorian prefect under the Caesar Julian and later a consul, before falling from grace when Julian became emperor. Titus Petronius Secundus (40–97) was a prefect of the Roman imperial bodyguard, known as the Praetorian Guard, under emperor Domitian, from 94 until 96.  Prior to becoming Praetorian prefect, Petronius had served as governor of the Egypt province from 92 until 93. Garmul was a Berber king of the Kingdom of Altava and successor of Mastigas in 541.  Garmul, who destroyed a Byzantine army in 571, launched raids into Byzantine territory, and three successive generals (the praetorian prefect Theodore and the "magister militum" Theoctistus in 570, and Theoctistus' successor Amabilis in 571) are recorded by John of Biclaro to have been killed in a battle by Garmul's forces.  His activities, especially when regarded together with the simultaneous Visigoth attacks in Spania, presented a clear threat to the province's authorities.  Thus the new emperor, Tiberius II Constantine, re-appointed Thomas as praetorian prefect, and the able general Gennadius was posted as "magister militum" with the clear aim of ending Garmul's campaigns.  Preparations were lengthy and careful, but the campaign itself, launched in 577–78, was brief and effective, with Gennadius utilizing terror tactics against Garmul's subjects.  Garmul was defeated and killed by 579, and the coastal corridor between Tingitana and Caesariensis secured. Claudia Capitolina (Greek: η Κλαuδία Καπιτωλίνα ) was an Egyptian Greek woman who lived in the Roman Empire, in the 1st century and possibly in the 2nd century.  Capitolina came from a distinguished family of Equestrian rank.  She was born and raised in Alexandria, Egypt.  Capitolina was the daughter and only child of Tiberius Claudius Balbilus by his unnamed wife.  The cognomen "Capitolina", is probably from her maternal side.  Her father was one of the highest magistrates of Equestrian rank that served in Rome.  Balbilus was an astrologer and a learned scholar, who was later Prefect of Egypt.  Capitolina’s paternal grandfather, was an Egyptian Greek Grammarian and Astrologer called Thrasyllus of Mendes or Tiberius Claudius Thrasyllus, who was a friend of the Roman Emperor Tiberius, while her paternal grandmother was Greek Princess Aka II of Commagene, who was a great, granddaughter of King Antiochus I Theos of Commagene.  Her paternal cousin was Ennia Thrasylla who married the Praetorian prefect of the Praetorian Guard, Naevius Sutorius Macro. <P0-S0> Marinus was one of the most trusted and senior aides of the Byzantine emperor Anastasius I (r. 491–518). <P0-S1>  He served twice as praetorian prefect of the East, supervised some of Anastasius's tax reforms, supported the Emperor's pro-Monophysite policies and led the Byzantine navy in a crucial battle that ended for good the rebellion of general Vitalian in Thrace. <P0-S2>  He survived into the regime of Justin I (r. 518–527), when he held his second tenure as praetorian prefect, but was soon sidelined from power. <P2-S0> Praetorian prefect (Latin: "praefectus praetorio" , Greek: ) was the title of a high office in the Roman Empire. <P2-S1>  Originating as the commander of the Praetorian Guard, the office gradually acquired extensive legal and administrative functions, with its holders becoming the Emperor's chief aides. <P2-S2>  Under Constantine I, the office was much reduced in power and transformed into a purely civilian administrative post, while under his successors, territorially-defined praetorian prefectures emerged as the highest-level administrative division of the Empire. <P2-S3>  The prefects again functioned as the chief ministers of the state, with many laws addressed to them by name. <P2-S4>  In this role, praetorian prefects continued to be appointed until the reign of Heraclius in the 7th century AD, when wide-ranging reforms reduced its power and converted it to a mere overseer of provincial administration. <P2-S5>  The last traces of the prefecture disappeared in the Byzantine Empire by the 840s. Casperius Aelianus, who served as Praetorian Prefect under the emperors Domitian and Nerva, was a Praetorian Prefect loyal to the Roman Emperor Domitian, the last of the Flavian dynasty.  After Domitian's murder and the ascension of the Emperor Nerva, Aelianus laid siege to the Imperial Capital in order to force the capture of the men responsible for Domitian's death, who had not been punished by Nerva.  Aelianus succeeded in his demands, greatly weakening the authority of the Emperor, so much so that Nerva realized that his position was no longer tenable without the support of an heir who had the approval of the Roman army.  Within two or three months Nerva announced the adoption of the highly respected general Trajan as his successor. The Roman Empire (Latin: "Imperium Rōmānum" ; ] Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr.  "Basileia tōn Rhōmaiōn" ) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia.  The city of Rome was the largest city in the world  100 BC  AD 400 , with Constantinople (New Rome) becoming the largest around AD 500, and the Empire's populace grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time).  The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC.  Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt.  Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title "Augustus", effectively marking the end of the Roman Republic. Successianus was a Roman soldier, general and praetorian prefect in the third century AD of whom very little is known for certain.  He is said to have distinguished himself as commander of the garrison of an allied city besieged by barbarian pirates, and then made praetorian prefect by the emperor Valerian on the strength of this.  As praetorian prefect appears to have done useful work in restoring "Antioch", the capital of the Roman East, after the devastation which had been inflicted by Shapur, the King of the Persians, in his invasion of 252.  However, he was overwhelmed by the circumstances with which he had to contend when Shapur invaded on a second occasion in 260 and seems to have shared in the defeat of Valerian at the Battle of Edessa and his subsequent captivity in Persia.

Supporting sentences:
The Roman Empire (Latin: "Imperium Rōmānum" ; ] Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr.  The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC.