Gregory was brought up at Clermont-Ferrand by his uncle Gallus and by his successor, Avitus, and there he received his education.
The classical accounts of the invasion of Aelius Gallus in 26 B.C. threw little light on the state of Arabia at the time, still less on its past history.
The emperor Gallus was forced to pay tribute to the Goths.
The invasion under Aelius Gallus was an absolute failure, the expedition being betrayed by the guides and lost in the sands of the desert.
It bears the inscription Colonia Vibia Augusta Perusia, so that the town must have become a colony in the reign of the emperor C. Vibius Trebonianus Gallus (A.D.
The lives, which (with few exceptions) are arranged in chronological order, are distributed as follows: - To Spartianus: the biographies of Hadrian, Aelius Verus, Didius Julianus, Septimius Severus, Pescennius Niger, Caracallus, Geta (?); to Vulcacius Gallicanus: Avidius Cassius; to Capitolinus: Antoninus Pius, Marcus Aurelius Antoninus, Verus, Pertinax, Clodius Albinus, the two Maximins, the three Gordians, Maximus and Balbinus, Opilius Macrinus (?); to Lampridius: Commodus, Diadumenus, Elagabalus, Alexander Severus; to Pollio: the two Valerians, the Gallieni, the so-called Thirty Tyrants or Usurpers, Claudius (his lives of Philip, Decius, and Gallus being lost); to Vopiscus: Aurelian, Tacitus, Florian, Probus, the four tyrants (Firmus, Saturninus, Proculus, Bonosus), Carus, Numerian, Carinus.
Columbanus was the first of the long stream of famous Irish monks who left their traces in Italy, Switzerland, Germany and France; amongst them being Gallus or St Gall, founder of St Gallen, Kilian of Wiirzburg, Virgil of Salzburg, Cathald of Tarentum and numerous others.
The following year, the question of the intervention of kings in the election of bishops having been raised in a pamphlet by Charles Hersent (Optatus Gallus de cavendo schismate, 1640), Marca defended what were then called the liberties of the Gallican Church, in his celebrated treatise De concordia sacerdotii et imperii, seu de libertatibus ecclesiae gallicanae (1641).
He has been identified with the Aelius Gallus frequently quoted by Galen, whose remedies are stated to have been used with success in an Arabian expedition.
When the Jews in Jerusalem, stirred to revolt by the outrages of the Roman procurators, had seized the fortress of Masada and treacherously murdered the garrison of the palace of Herod, Gallus set out from Antioch to restore order.