3. Q.Cornificius, son of No. 2, is first mentioned in B. C. 50, as betrothing himself to the daughter of Aurelia Orestilla, the beautiful but profligate widow of Catiline. (Cic. Fam. 8.7.) In the civil war between Caesar and Pompey, he served in 48 as the quaestor of the former, by whom he was sent into Illyricum with the title of propraetor. By his prudence and military skill, Cornificius reduced the province to a state of obedience, and rendered no small service to Caesar's cause. (Hirt. B. Alex. 42.) He seems to have returned to Rome in the following year, and was then probably rewarded by Caesar with the augurate, as we find, from Cicero's letters, that he was in possession of that office in the next year. He also formed an intimate friendship with Cicero, several of whose letters to him are extant. (Ad Fam. 12.17-30.)

Cornificius did not remain long in Rome. In B. C. 46, we find him in Syria, where he was observing the movements of Caecilius Bassus, and in the beginning of the following year he was appointed by Caesar governor of Syria. (Cic. Fam. 12.18, 19.) This office, however, he did not hold long, for on the death of Caesar, in B. C. 44, be was in possession of the province of Old Africa. This he maintained for the senate against L. Calvisius Sabinus, and continued to adhere to the same party on the formation of the triumvirate, in 43. He sent troops to the assistance of Sex. Pompey, and gave shelter and protection to those who had been proscribed by the triumvirs. He refused to surrender his province to T. Sextius, who commanded the neighboring province of New Africa, and who had ordered him, in the name of the triumvirs, to do so. Hereupon a war broke out between them. The details of this war are related somewhat differently by Appian and Dio Cassius; but so much is certain, that Cornificius at first defeated T. Sextius, but was eventually conquered by the latter, and fell in battle. (Appian, App. BC 3.85, 4.36, 53-56; D. C. 48.17, 21; Liv. Epit. 123.)

Cornificius was a man of literary habits and tastes. Cicero speaks highly of his judgment when he sends him in B. C. 45 a copy of his "Orator," but seems to banter him somewhat respecting his oratory. (Cic. Ad Fam. 12.17, 18.) Many have attributed to him the authorship of the " Rhetorica ad Herennium." Some remarks are made on this subject below.

The following coin refers to this Cornificius. It bears on the obverse the head of Ammon, and on the reverse Juno holding a shield and crowning a man who has a lituus in his right hand, with the legend Q. CORNVFICI AVGVR IMP. From the head of Ammon, it would appear to have been struck in Africa, and the title of Imperator was probably given him by his soldiers after his victory over T. Sextius.