In the war against the Cimbri and Teutones he was sent to defend the passage of the Alps but found himself compelled to retreat across the Po River, his troops having been reduced to a state of panic. But the Cimbri were defeated on the Raudine plain, near Vercellae, by the united armies of Catulus and Marius. When the chief honour was given to Marius, Catulus became his bitter opponent. He sided with Sulla in the civil war, was included in the proscription list of 87, and when Marius declined to pardon him, committed suicide.
He was distinguished as an orator, poet and prose writer, and was well versed in Greek literature. He is said to have written the history of his consulship and the Cimbrian War after the manner of Xenophon; two epigrams by him have been preserved, one on Roscius the celebrated actor (Cicero, De Nat. Deorum, I. 28), the other of an erotic character, imitated from Callimachus (Gellius xix. 9).
Catulus was a man of great wealth, which he spent in beautifying Rome. Two buildings were known as "Monumenta Catuli": the temple of Portuna hujusce dei, to commemorate the day of Vercellae, and the Porticus Catuli, built from the sale of the Cimbrian spoils. See Plutarch, Marine, Sulla; Appian, B.C. i. 74; VeIl. Pat. ii. 21; Florus iii. 21; Val. Max. vi. 3, ix. 13; Cicero, De Oratore, iii, 8, Brutus, 35.