The Praetorian Prefects under the Julio-Claudians are described.
Was it a good career path to become a prefect of the Praetorian Guard under the Julio-Claudians? This question is debated.© SolutionLibrary Inc. solutionlibary.com 9836dcf9d7 https://solutionlibrary.com/history/ancient-history/the-praetorian-prefects-under-the-julio-claudians-are-described-1v4
...Livilla, which was at first put off by Tiberius in 25 and then finally announced in 31, after Sejanus's attainment of the proconsular imperium. The second was the betrothal of a son of Claudius to the daughter of Sejanus. Sejanus would have then covered all the bases in his desire to put forward his own family in a position of easy grasp of the principate after the elimination of the rest of the Julian line and of Tiberius's own descendants. But these plans were all in vain and finally, the end had to come sooner or later. And it was with surprising speed that it happened.
Finally, Tiberius, spurred on by the "Antonia" letter and by his other suspicions, must have started to act even as he was piling honors on Sejanus. For instance, the varying tones of Tiberius's communications to the Senate towards the end did not help those who were wavering to make up their minds to support the prefect. Tiberius probably did this to keep Sejanus bewildered and also to gauge the feelings of the Roman people towards the minister (and to himself). In these, sometimes Tiberius would be warm towards Sejanus, sometimes glacial: this must have not helped the minister's cause in the Senate. When Nero died, Tiberius sent a letter omitting Sejanus's usual titles. Sejanus can almost be seen as a victim here, and Syme (and Dio as well) considers him one. Also, in another quite cunning move, Tiberius forbade any cult to a living human being, which included himself - and Sejanus. This was actually a restoration of a previous law, but Tiberius had a definite purpose in repeating it here. Then Tiberius, when giving a priesthood to Sejanus and his son, also gave one to Gaius. He also probably insured, by using an agent called Lentulus, that when an enemy of Sejanus, L. Arruntius Camillus Scribonianus, was indicted in the Senate, the charges would be dropped. Tiberius also raised P. Memmius Regulus to the consular college, which gave him a dependable asset in his battle to the finish against the prefect. Indeed, Tiberius sent the instructions that Macro was to relay to the praetorian guards to two men: Memmius Regulus, and the prefect of the vigiles, Graecinus Laco, when the time came to get rid of Sejanus. Tiberius had also prepared to flee by sea to a nearby legion, so he was not interested in abdicating, but would have fought to remain in power. Here we had a fight between the real "founder" of the praetorian cohorts as they were known throughout the early principate and between a cunning and wily princeps. Tiberius was eventually to win this, but it was never a sure thing that he would, because he was not sure of the loyalty of the Senate and the Praetorian Guard. It is my opinion that he did not have to really worry about the Senate, who viewed this "upstart" would-be consular novus homo with distrust and enmity. However, it could have gone either way with the Guard: this is why Macro was sent with the promise of a donative as a balm for the men to the loss of their commander, and also why the Praetorians at the Senate were replaced with vigiles on that particular day. Tiberius's letter to the Senate was also very long and meandering, to give Macro time to follow his orders and organize the Praetorian takeover. The letter also variously praised and blamed Sejanus, thus keeping him off guard and not allowing him time to organize his thoughts. Finally, there were orders in the letter to arrest Sejanus and two of his followers immediately and the orders were gladly followed by a grateful Senate. Tiberius had plotted well, and even if he was still secluded in Capri, and never to come back to Rome, still showed a mastery of politics that eluded the proud prefect and cost him his position and his life.
For Sejanus, the position of Praetorian Prefect had been a lure to the glittering prize of imperial power that culminated in false hopes and in an untimely end. A few prefects that followed understood what had happened here and tried to keep more or less quiet and thus escaped with their life, if not always with their position. But some, such as Tigellinus and Nymphidius Sabinus, did not learn the lesson taught by the acts of Sejanus, and they were also to regret not heeding this warning, in other words, the consequences that ensued from their holding the top equestrian post and being overly ambitious, greedy or arrogant, as we shall see later.
Macro, or the helper betrayed
Macro was appointed praetorian prefect by Tiberius when the emperor had decided to get rid of Sejanus. Macro was known by Tiberius to be loyal. Indeed, he had served Tiberius well as prefect of the vigiles beforehand. Macro got the job done when came the time to bring Tiberius's instructions to the Senate (in the form of a very long, meandering letter), and to the Praetorian Guard, whom he convinced to remain quiet in their barracks on that fateful day of October 31.
Q. Naevius Cordus Sutorius Macro came from Alba Fucens, where he was born in 21 BC. He was part of the Fabia tribe of the region. He became prefect of the vigiles under Tiberius. It was not the most powerful of positions, as compared to the other prefectures, like the praetorian prefecture or that of Egypt, but it allowed Macro to make himself a devoted following of men, which was to help him later on when the time came to take care of Sejanus. One of these men was Gaecinus Laco, his successor to the prefecture of the vigiles, who obeyed instructions from the emperor and his old leader with no hesitations on the day Sejanus fell.
It is also thought that Macro played the role of the "eyes" in Rome of the absent emperor as well. Macro certainly seemed to be the prototype of the stern, all-obeying prefect, but also a good leader of men and a inspirer of trust in the two principes he served - up to a certain point with Caligula, however. Macro was also chosen by Tiberius to accompany him, if and when he went to the Senate-house, which of course, he never did again. Macro also played a major role in the prosecution of Sejanus's followers, and got rid of a great many friends of the ex-prefect and a lot of his own enemies in that manner.
Macro then attached himself to the growing fortune of the young Caligula, and did all that he could to promote him as a successor to Tiberius, and obtained more and more power in the process. Macro then married Ennia Thrasilla, niece of Tiberius's astrologer and encyclopedist Thrasyllus. Caligula took a fancy to the bride and soon established himself as her lover, and even promised to marry her. It is debatable that Macro was a willing instrument in this. Eventually, Macro obtained Tiberius's assentment to the succession going to the young Gaius (albeit jointly with the emperor's grandson Tiberius Gemellus) and went to Rome to prepare the way for the succession.
On the 16th of March, AD 37, Tiberius lay dying. Some stories have him coming out of a coma and asking for his signet ring, to the dismay of Caligula who thought he was now emperor. Macro and/or Caligula poisoned or smothered him to ensure that he was really dead, according to some. Macro had moved fast and efficiently in Rome: there was no opposition to the young emperor's accession, and the prefect had prepared a triumphant procession and entry into the capital for the new ruler; the people cheered and made many sacrifices to Caligula: indeed, "The magic of Germanicus's name and Macro's efforts had aroused enthusiasm far and wide". Macro also had sent agents to governors and legions in order that Caligula be proclaimed emperor by them as soon as possible. Macro administered the oath to Caligula to the men and sailors stationed in Naples when Tiberius died as well. In Rome, the Praetorians stayed quietly in their barracks and did not oppose the new princeps and were rewarded with a donative for this, the first time that this acknowledgement of a debt for an accession had been known to happen to the Praetorian Guard.
Gaius then had Macro bring Tiberius's will to the Senate and then read by the prefect and after that, had it declared null and void, thus removing Tiberius Gemellus from the succession picture. Caligula then started getting tired of Antonia's interference and may have provoked his grandmother's death by treating her with great disrespect, including forcing her to come to meet him only in the presence of Macro. But she had been given great honors beforehand by Caligula, including rights that Livia had once had, including a priesthood of Augustus and the title of Augusta, so this is debatable.
In AD 38, Caligula was starting to get tired of Macro's authoritarian and stern ways, however. When he saw Macro getting close, he would "put on a cross air". Also Macro, nominated to replace Avilius Flaccus as prefect of Egypt, had the bad luck to be friends with his predecessor, whom Caligula had effectively disgraced because he was a supporter of Tiberius Gemellus as successor of Tiberius, which was an unforgivable offence in the emperor's eyes.
This was the beginning of the end for Macro, as Caligula went into a incredibly violent invective against the prefect and his wife in the Senate, even though Macro had just been made prefect of Egypt. Finally, Macro and his wife Ennia were forced to suicide. 
So we now realize that ambition did not work to keep one prefect alive, and now another had perished because he had the wrong friends, even though he had proven himself loyal to his ruler. Also, if Macro had actually killed Tiberius, maybe Caligula felt uneasy with a prefect that had already killed one emperor and could easily kill another, even though Macro had proven himself to be utterly loyal? This could be a reason for the death of another prefect, in a job that seemed more and more dangerous. Who would be the next to be in this hot seat and how would they react to the possession of this power?
M. Arrecinus Clemens and the death of Caligula
Caligula then appointed two new prefects in 38, Marcus Arrecinus Clemens and possibly L. Arruntius Stella. Clemens was probably from the Camilia tribe of the Pesaro region, near Rimini. His daughter eventually married the future emperor Titus and his son M. Arrecinus Clemens was also appointed prefect of the Praetorians in 70. Clemens was most likely involved in the successful conspiracy to kill Caligula in AD 41 and the other prefect may have been involved too.
In AD 40, the prefects had been accused of being accomplices in a conspiracy against Caligula by Capito, who had pretended to be involved and promised to tell the names of the other conspirators to the emperor. Capito was found to be exaggerating when he told the names of the prefects and of close associates of Caligula (and he said Callistus and Caesonia were involved as well), so he was not believed. Caligula then took his prefects and Callistus aside and told them that they were three and could easily slay him if they hated him. After this, Caligula, believing he was hated, always wore a sword when he was in Rome, and tried to set them up against each other.
Eventually, a plot was hatched by some senators and some tribunes of the Praetorian Guard, including Cassius Chaerea and Cornelius Sabinus. The prefects were involved up to a point, as they both surely knew about the plot, if not participating in it actively. Indeed, Clemens may have excused himself by stating his old age, but gave his blessing to the plotters, while cautioning them to keep quiet about the plot.  Durry argues that Clemens and his colleague actually prepared the assassination themselves; also, Ferrill states that they were actually part of the conspiracy.
During the murder, the prefects were not as active as their tribunes, but Arruntius Stella eventually calmed down the German guards, who were very angry about the attempt on Caligula's life, by telling them the princeps was dead. And Clemens was telling as many senators as he could that the "deed was just", and made a speech about Gaius actually having, in effect, killed himself by his own actions.
After the deed had been done, the Praetorians secured the palace and recovered Caligula's uncle Claudius, the last Julio-Claudian candidate for the principate, which they eventually took to be their own candidate as emperor. As for the assassins, Claudius, after his elevation, eventually put Chaerea to death, and Sabinus soon killed himself; however, the prefect (or prefects) were spared but replaced immediately by Rufrius Pollio and possibly Catonius Iustus.
So this time, the prefect (or prefects) lost his position, but not his life. At least, these men were involved in getting Rome rid of a terrible and dangerous ruler, and Clemens was actually later praised as having done his duty in an "admirable" manner under Caligula.
Claudius's prefects - a revolving door?
If one man of the Julio-Claudian dynasty owed a lot to the Praetorians, it was surely Claudius. And he acknowledged this debt readily, especially with an accession donative to the men - and coins in which his ties to the Guard are well advertised. As for the prefects of his reign, he began by immediately replacing one of Gaius's prefects, possibly Arrecinus Clemens, but most likely the other one, whose name may have been Arruntius Stella.
The replacement's name was Rufrius Pollio, and he seems to have done well by Claudius. Indeed, when Claudius went to Britain in 43, he took along Pollio for the trip. The crowning glory of the prefect's career was the image and seat he was granted in the Senate by the emperor.
Another prefect who came to power around the same time as Pollio, Catonius Iustus, was not so lucky in his career. He was trying to inform Claudius of Messalina's intrigues, but did not make it before he was killed in AD 43.
The consular L. Vitellius was so trusted by Claudius that when the emperor left for Britain in 43, he made Vitellius prefect of the City, and of the Guard as well, probably for the duration of the campaign.
Then Rufrius Crispinus and Lusius Geta replaced Pollio and Iustus (or Vitellius) and held power over the Praetorian Guard possibly from 43 to 51 or 52.
Rufrius Crispinus was devoted to Messalina and wanted to help her in her conquest of the actor Mnester by arresting her rival Sabina Poppea's friend Valerius Asiaticus; she also wanted the Gardens of Lucullus, which happened to belong to Asiaticus. Crispinus was well-rewarded for all of this; he was given money and the praetorship or its insignia. When the time came to take care of the "marriage" conspiracy of Silius and Messalina, he was nor present with Claudius and the emperor also judged him unreliable, so he didn't use him against his errant wife. Eventually, Claudius married Agrippina, who promptly fired both prefects. Rufrius eventually came to an untimely end when he was caught plotting against Nero and was first banished to Sardinia, then forced to suicide. Later on, his ex-wife, Poppea, was "given" to the future emperor Otho by Nero, and eventually married by the "artist-emperor" himself.
As for Lusius Geta, he was a supporter of Messalina and her children as well, which is why he was not entirely trusted during the Silius "marriage" conspiracy. Claudius, who was with Geta in Ostia at one point during this crisis, asked him if he was still in power. Geta was trusted so little that Narcissus asked Claudius to put a freedman in charge of the Guard, preferably himself. And some say that Narcissus got his wish on that particular day. Geta eventually lost his post when Agrippina replaced him and Crispinus with Burrus. ...