Roman emperor, A. D. 383-388. in Gaul, Britain, and Spain, was a native of Spain (Zosim. iv. p. 247), but not of England, as modern authors assert. He boasted of being a relation of his contemporary. the emperor Theodosius the Great, though the fact is that he had merely lived some years in the household of that emperor in a subordinate capacity. He was of obscure parentage; an uncle of his, however, is mentioned in history, and also a brother, Marcellinus, whose name will appear again in the course of this sketch. Maximus accompanied Theodosiua on several of his expeditions, was promoted, and, perhaps as early as A. D. 368, proceeded with his master to Britain, where he remained many years in the quality of a general, as it seems, but decidedly not as governor of that province, as some modern writers of eminence pretend. It is said that he married Helena, the daughter of Eudda, a rich noble of Caersegont (Caernarvon in Wales), but the authority is more than doubtful. (Comp. Gibbon, c. xxvii. p. 7, note k. ed. 1815, 8vo.) The predilection of the emperor Gratian for foreign barbarians excited discontent among the legions in Britain, which were the most turbulent in the whole Roman army. Maximus is said to have secretly fomented their disaffection, and thus a terrible revolt broke out which led to the accession of Maximus and the ruin of Gratian. Zosimus, though by no means a detractor of Maximus, charges him with having acted thus; but Orosius and Sulpicius Severus both state that the troops had forced Maximus, who was known as a man of principle and merit, to accept the imperial dignity, which was offered him by the rebels; and Orosius says that he solemnly protested his innocence. However this may be, Maximus was proclaimed emperor in A. D. 383 (not in 381 as Prosper states in his A short time before his accession he had adopted the Christian religion.

Maximus immediately gave orders to all the troops stationed in Britain to assemble as soon as possible, and he lost no time in attacking Gratian in Gaul. It is related in the life of Gratian that he was defeated by the usurper near Paris, deserted by his general Merobaudes, a Frankish chief, and finally slain near Lyon, on his flight to Italy, by Andragathius, who pursued him by order of Maximus. The sudden overthrow of the power of Gratian was followed by the as sudden and complete establishment of the power of Maximus: Gaul, Spain, and Britain did homage to the fortunate usurper, who associated his son Victor with him, proclaiming him Caesar, and perhaps Augustus; and the new emperor took up his residence at Trèves, where there are still some monuments extant of his reign. No persecutions were instituted against the adherents of Gratian, except Merobaudes and Balio or Vallio, who lost their heads on account of their ambiguous conduct, and it seems that, with these exceptions, Maximus was not wrong when, in later times, he boasted that his elevation had caused no loss of Roman life except on the field of battle. Yet even Merobaudes and Vallio were not Romans but barbarians. When the news of the downfall of Gratian and the success of Maximus reached Theodosius, he resolved to wrest the crown from the usurper, but ambassadors arrived from Maximus with peaceful offers, backed by stern declarations of sacrificing every thingforthe maintenance of his power; and as Theodosius was then unable to wage war with a rebel who was popular among the experienced and bold veterans of the West, he accepted the propositions made to him. Maximus was, in consequence, recognised by Theodosius and Valentinian as Augus tus and sole emperor in Gaul, Spain, and Britain, while the new emperor in his turn promised not to molest Valentiman in the possession of Italy and Hlyricum, which he had held already in the time of his brother Gratian.

Nothing now prevented Maximus from enjoying his power, and promoting the happiness of his subjects, but two circumstances, each of which was sufficient to foretell a future commotion. The professed friendship of Theodosius was not real, and the unparalleled success of Maximus swelled his ambition so much that he stepped beyond those limits of wisdom within which he ought to have kept his future plans. Italy was governed by a feeble youth, but who might become dangerous when a man, unless he forgot that he was the brother of a murdered emperor. The possession of Italy was therefore the great object at which Maximus aimed; and the revenues of his vast dominions were exhausted to form an army, the contingents of which were raised among the most warlike barbarians oi the time. Yet less confident in armls than in intrigues, Maximus prevailed upon the ministers of young Valentinian to accept from him auxiliaries for an intended war in Pannonia; and, although his motives were seen through by St. Ambrose and the other councillors of Valentinian, the forces of Maximus were allowed to cross the passes of the Alps (387). In their rear followed Maximus with his main army, and while the inhabitants of Milan, where the imperial court of Italy then resided, expected to welcome allies, they and their master were terrified by the sudden and unaccountable appearance of a hostile army under their walls. Flight was the only means of safety for Valentinian. Without loss ot time he escaped with his mother Justina to Aquileia, and thence by sea to Thessalonica, whence he despatched messengers to Constantinople to apprise Theodosius of his fate. Maximus entered Milan in triumph, and Rome and the rest of Italy soon submitted to him almost without a struggle.

The alarm of Theodosius at hearing at once of the loss of Italy, the disgrace of a weak yet beloved colleague, and the triumph of a hated rival, may be easily imagined. Instead of inviting Valentinian to proceed to Constantinople, he hastened, without losing any time, to Salonica, accompanied by his principal ministers, and then, with the fugitive emperor and his mother Justina, concerted measures to check the threatening course of the British conqueror. His love for Valentinian's sister Galla added wings to his resolution: in the midst of his preparations for bloodshed and war he married that beautiful princess, and then set out to encounter the legions of Gaul. Maximus, meanwhile, prepared for resistance by sea and land. Andragathus covered the coast of Italy with a powerful fleet, and the emperor concentrated his troops near Aquileia, despatching his van into Noricum and Pannonia, in order to receive Theodosius in that quarter if he should choose to come by land. Theodosius did come by land, and in the first engagement at Siscia, on the Save, the Western troops were completely defeated: they suffered a second defeat, being then commanded by Marcellinus. the brother of Maximus; and now Theodosius broke through the Noric Alps into Italy. Maximus, flying before him, took refuge within the walls of Aquileia, arriving there nearly at the same time as his pursuers. The troops of Theodosius immediately stormed the city, and with such energy that they took it at once, and seized Maximus, it is said, while seated on his throne. Theodosius was waiting the issue at his head-quarters, three miles from Aquileia. Thither Maximus was carried, loaded with chains. With a stern yet calm voice Theodosius reproached him for his rebellion against Gratian and unbounded ambition, and then gave orders for his decapitation, which took place on the same day (27th or 28th of August, 388). Victor, the son of Maximus, being then engaged in Gaul against the Franks, Arbogastes marched against him with a strong force. Victor was defeated and taken prisoner, and shared the fate of his father. Andragathus, the commander of the fleet of Maximus, upon hearing of the death of his master, threw himself in a fit of despair into the sea and was drowned. Theodosius was merciful and generous towards the mother and sisters of his fallen rival; but he nullified all the laws issued by Maximus. Valentinian nominally succeeded Maximus in the possession of Italy and the country beyond the Alps, but the real emperor was Theodosius. (Zosim. iv. p. 247, &c. ed. Oxon. 1679, 8vo.; Sozomen. 7.12, &c.; Oros. 7.34, &c.; Socrates, H. E. v. H l,&c.; Rufin. 2.14-17; Greg. Turon. Hist. Franc. 1.43; Ambros. Enarratio in Psalm. LXI. (in the first vol. of his works, p. 961), Epistol. XXIV. in vol. ii. p. 888, ep. 40, p. 952. &c., De Obitu Valentin. ibid. p. 1] 82, in the Benedictine ed.; Sulpic. Sever. Vita B. Martini, 100.23, Dialog. 2.7, 3.15; Pacatus, Panegyric. Theodosii, in " Panegyr. Vet." xii.; Prosper, Chron.; Marcellin. Chron.; Theoph. p. 57, &c. ed. Paris.)