Question: Gaius Calvisius Sabinus was a consul under the alliance formed on what date?
Context: Gaius Laelius C.f. Sapiens (born c. 188 BC), was a Roman statesman, best known for his friendship with the Roman general and statesman Scipio Aemilianus (Scipio the Younger) (d. 129 BC).  He was consul of 140 BC, elected with the help of his friend, by then censor, after failing to be elected in 141 BC.  Gaius Laelius Sapiens was the son and heir of the Punic war general Gaius Laelius himself consul in 190 BC.  This Laelius had been former second-in-command and long-time friend, since childhood, of the Roman general and statesman Scipio Africanus.  The younger Laelius was apparently born around 188 BC, after his father had become consul but had failed to win command of the campaign against Antiochus III the Great of Syria which would have made him a rich man.  His mother's name is unknown. Marcus Atilius Regulus (fl.  213 BC), a son of Marcus Atilius Regulus, the consul captured during the First Punic War, and a grandson of Marcus Atilius Regulus (consul 294 BC), was a Roman consul for the year 227 BC, together with Publius Valerius Flaccus, and was a consul "suffectus" in 217 BC, replacing Gaius Flaminius Nepos, who was killed in battle at Lake Trasimene.  Marcus Atilius Regulus agreed to accompany the consuls of 216 BC, Gaius Terentius Varro and Lucius Aemilius Paullus, along with the other surviving former consul of 217 BC, Gnaeus Servilius Geminus, when an army of 80,000 Romans and allies was amassed together to smash the Carthaginian army under Hannibal.  The historian Polybius records that both he and Servilius died fighting bravely at the Battle of Cannae. The Second Triumvirate is the name historians have given to the official political alliance of "Gaius Julius Caesar Octavianus" (Caesar Augustus), "Marcus Antonius" (Mark Antony), and "Marcus Aemilius Lepidus", formed on 27 November 43 BC with the enactment of the "Lex Titia", the adoption of which is viewed as marking the end of the Roman Republic.  The Triumvirate existed for two five-year terms, covering the period 43 BC to 33 BC.  Unlike the earlier First Triumvirate, the Second Triumvirate was an official, legally established institution, whose overwhelming power in the Roman state was given full legal sanction and whose "imperium maius" outranked that of all other magistrates, including the consuls. Gaius Calvisius Sabinus was consul in AD 26 with Gnaeus Cornelius Lentulus Gaetulicus.  During the reign of Caligula, he was accused of conspiring against the emperor, and took his own life rather than submit to a trial. Gaius Calvisius Sabinus was a consul of the Roman Republic in 39 BC under the Second Triumvirate.  He and his consular colleague Lucius Marcius Censorinus had been the only two senators who tried to defend Julius Caesar when his assassins struck on 15 March 44 BC, and their consulship under the triumvirate is taken as a recognition of their loyalty.  An inscription, described by Ronald Syme as "one of the most remarkable inscriptions ever set up in honour of a Roman senator," praises Calvisius for "pietas", his sense of duty or devotion.  As a military officer, Calvisius is notable for his long service and competence, though he was not without serious defeats. The gens Calvisia was a Roman family, which first rose to prominence during the final decades of the Republic, and became influential in imperial times.  The first of the gens to obtain the consulship was Gaius Calvisius Sabinus in 39 BC. Calvisius Sabinus, whose "praenomen" is not recorded, was a wealthy contemporary of the younger Seneca. Gaius Calvisius Sabinus (born c. 36 BC) was a Roman Senator who was appointed Roman consul in 4 BC. Lucius Marcius Censorinus was a consul of the Roman Republic in 39 BC, during the Second Triumvirate.  He and his colleague Gaius Calvisius Sabinus had been the only two senators who tried to defend Julius Caesar when he was assassinated on the Ides of March in 44 BC, and their consulship under the triumvirate was a recognition of their loyalty. Titus Flavius T. f. T. n. Clemens was a nephew of the Roman Emperor Vespasian.  He was the son of Titus Flavius Sabinus, consul in AD 47 and "praefectus urbi" during the reign of Nero, and a brother of Titus Flavius Sabinus, consul in AD 82.  The emperors Titus and Domitian were his cousins.
Answer: 27 November 43 BC