Born sometime before 97 BC, son of a Publius Lentulus, his origins are otherwise unknown, though he was most likely a member of the
patrician Cornelii Lentuli branch of the
gens Cornelia. Details of Crus' younger years are not known. In 72 BC, Caesar's man Balbus acquired his
Roman citizenship for service under Pompeius against
Quintus Sertorius in Spain. On the basis of the Roman names he took – Lucius Cornelius Balbus – and on the basis of later letters to Cicero, it is possible that both Balbus
major and
minor obtained citizenship with the sponsorship of L. Cornelius Lentulus Crus, who may then have been serving with Pompeius as a
legate (Pompeius was there 76 BC to 71 BC; had Crus been born c. 98 BC, he would have been between the ages of 22 and 27 at the time). In 61 BC he was the chief prosecutor of
Publius Clodius Pulcher at a
quaestio extraordinaria over the latter's violation of the mysteries of the
Bona Dea, along with two other Cornelii Lentuli, in which he failed to secure a conviction due in large part to the bribes which Clodius spread among the jurors. Lentulus' rise through the
cursus honorum of political office is not now known prior to his election, during the consulship of Caesar and
Bibulus, as
Praetor for 58 BC. During his term of office Clodius, now a
tribune of the people, moved against his enemy
Cicero on the basis that the latter, as consul of 63 BC, had put Roman citizens to death without trial. Cicero hoped for Lentulus' aid against Clodius; although the praetor did, with other senior figures, attempt to persuade Pompeius to act to protect Cicero, this failed, as Pompeius refused to act against an elected tribune on his own authority. In 51 BC he stood for election to the prestigious priestly board of fifteen men in charge of the
Sibylline Books (
Quindecimviri sacris faciundis), but was defeated by
Publius Cornelius Dolabella (to the amusement of Cicero's correspondent,
Marcus Caelius Rufus). In 50 BC he was elected consul for the following year alongside
G. Claudius Marcellus, as opponents to Caesar, and was an active and vocal participant in the increasingly hysterical scenes in the senate in late 50 and January 49 as Caesar sought to secure a safe consulship while a reactionary group of senators sought to have him stripped of command. Finally, on 7 January 49 BC, the senate under Lentulus and Marcellus passed the "final decree" (
senatus consultum ultimum); the tribunes
Mark Antony and
Quintus Cassius fled with Caesar's envoy, the younger
Curio, from Rome to meet Caesar at
Ravenna. On the 10th, Caesar famously crossed the
Rubicon, starting the Civil War. ==Civil War==