Gnaeus Calpurnius Piso (fl. 1st century BC) was a Roman Senator who was appointed the replacement consul in 23 BC.
Calpurnius Piso was the son of Gnaeus Calpurnius Piso, one of the participants in the Catiline Conspiracy. A defender of the traditional senatorial elite and an opponent of the First Triumvirate, he first came to notice sometime during the 50 BCs when he prosecuted Gaius Manilius Crispus, a Plebeian Tribune who was in the employ of Gnaeus Pompeius Magnus. Although Crispus was obviously guilty, the influence of Pompeius was making an acquittal look increasingly likely. Calpurnius Piso, in frustration, began to accuse Pompeius of a number of serious charges during the course of the trial. When Pompeius asked Calpurnius Piso why Piso did not prosecute him as well, Piso retorted:
”Give me a guarantee that you will not wage a civil war against the Republic if you are prosecuted, and I shall at once send the jurymen to convict you and send you into exile rather than Manilius.”
With Pompeius joining the conservative senators and the outbreak of the civil war against Julius Caesar, Calpurnius Piso was sent to Hispania Ulterior in 49 BC, where he served as a Proquaestor under Pompeius’ legates. The defeat of the Pompeian forces saw Calpurnius Piso cross over to North Africa. In 46 BC he served under Quintus Caecilius Metellus Pius Scipio Nasica and was given command of the Moorish cavalry. With the republican defeat at the Battle of Thapsus he seemed to come to terms with Caesar’s victory, but with the dictator’s assassination in 44 BC, he aligned himself with the Liberatores, joining the armies of Gaius Cassius Longinus and Marcus Junius Brutus the Younger. With their defeat at the Battle of Philippi in 42 BC, Piso was eventually pardoned. However, on his return to Rome he refused to participate in the political arena under the domination of Caesar’s heir, Caesar Octavianus (the future Augustus). He therefore withdrew from active political life.
Succession crisis of 23 BC
In 23 BC, the domination of Augustus began to cause the emperor some political difficulties, which were compounded by his apparent desire to groom his nephew Marcellus as his political heir. Problems in the political alliance between Augustus, Livia, Maecenas and Marcus Vipsanius Agrippa over his succession plans saw Augustus search around for potential support within the Senate. With the death of the consul-elect Aulus Terentius Varro Murena prior to his assuming office, Augustus offered the consulship to the noted republican and imperial opponent Calpurnius Piso.
Although Augustus clearly hoped to win Piso over, and in the process not only deflect attention away from Marcellus but also to reinforce the fiction that the republic still functioned, it is unclear why Piso accepted the role after so many years of rejecting the legitimacy of the principate. Explanations ranging from a sense of public duty, to a resurgence of his political ambitions, to resurrecting his family's 'dignitas' after a long period of obscurity, with the hope of consulships for his two sons have all been offered.
However, as the year progressed, Augustus fell seriously ill. He gave up the consulship, and as his condition worsened, he began to make plans for the stability of the state should his death come about. Augustus therefore handed over to his co-consul Piso all of his official documents, an account of public finances, and authority over listed troops in the provinces, declaring his intent that Piso, as consul, should take over the functioning of the state for the duration of his consulship. However, Augustus’ signet ring was handed to Agrippa, a clear indication that the legions were to follow Agrippa and not Piso.
After Augustus’ recovery, Calpurnius Piso completed the remainder of his term without incident. There is no further record of his filling any other post after his consulship.
Calpurnius Piso married a daughter of a Marcus Popillius and they had at least two sons: Gnaeus Calpurnius Piso, consul of 7 BC, and Lucius Calpurnius Piso, consul in 1 BC.