On the expedition he carefully disciplined and trained his army whilst on their way, giving them practice in long marches, and running of every sort, and compelling every man to carry his own baggage and prepare his own victuals; insomuch that thenceforward laborious soldiers, who did their work silently without grumbling, had the name of "Marius's mules." Some, however, think the proverb had a different occasion; that when Scipio besieged Numantia, and was careful to inspect not only their horses and arms, but their mules and carriages too, and see how well equipped and in what readiness each one's was, Marius brought forth his horse which he had fed extremely well, and a mule in better case, stronger and gentler than those of others; that the general was very well pleased, and often afterwards mentioned Marius's beasts; and that hence the soldiers, when speaking jestingly in the praise of a drudging, laborious fellow, called him Marius's mule.

But to proceed; very great good fortune seemed to attend Marius, for by the enemy in a manner changing their course, and falling first upon Spain, he had time to exercise his soldiers, and confirm their courage, and, which was most important, to show them what he himself was. For that fierce manner of his in command, and inexorableness in punishing, when his men became used not to do amiss or disobey, was felt to be wholesome and advantageous, as well as just, and his violent spirit, stern voice, and harsh aspect, which in a little while grew familiar to them, they esteemed terrible not to themselves, but only to their enemies. But his uprightness in judging, more especially pleased the soldiers, one remarkable instance of which is as follows. One Caius Lusius, his own nephew, had a command under him in the army, a man not in other respects of bad character, but shamefully licentious with young men. He had one young man under his command called Trebonius, with whom notwithstanding many solicitations he could never prevail. At length one night, he sent a messenger for him, and Trebonius came, as it was not lawful for him to refuse when he was sent for, and being brought into his tent, when Lusius began to use violence with him, he drew his sword and ran him through. This was done whilst Marius was absent. When he returned, he appointed Trebonius a time for his trial, where, whilst many accused him, and not any one appeared in his defense, he himself boldly related the whole matter, and brought witness of his previous conduct to Lusius, who had frequently offered him considerable presents. Marius, admiring his conduct and much pleased, commanded the garland, the usual Roman reward of valor, to be brought, and himself crowned Trebonius with it, as having performed an excellent action, at a time that very much wanted such good examples.

This being told at Rome, proved no small help to Marius towards his third consulship; to which also conduced the expectation of the barbarians at the summer season, the people being unwilling to trust their fortunes with any other general but him. However, their arrival was not so early as was imagined, and the time of Marius's consulship was again expired. The election coming on, and his colleague being dead, he left the command of the army to Manius Aquilius, and hastened to Rome, where, several eminent persons being candidates for the consulship, Lucius Saturninus, who more than any of the other tribunes swayed the populace, and of whom Marius himself was very observant, exerted his eloquence with the people, advising them to choose Marius consul. He playing the modest part, and professing to decline the office, Saturninus called him traitor to his country, if, in such apparent danger, he would avoid command. And though it was not difficult to discover that he was merely helping Marius in putting this presence upon the people, yet, considering that the present juncture much required his skill, and his good fortune too, they voted him the fourth time consul, and made Catulus Lutatius his colleague, a man very much esteemed by the nobility, and not unagreeable to the commons.

Marius, having notice of the enemy's approach, with all expedition passed the Alps, and pitching his camp by the river Rhone, took care first for plentiful supplies of victuals; lest at any time he should be forced to fight at a disadvantage for want of necessaries. The carriage of provision for the army from the sea, which was formerly long and expensive, he made speedy and easy. For the mouth of the Rhone, by the influx of the sea, being barred and almost filled up with sand and mud mixed with clay, the passage there became narrow, difficult, and dangerous for the ships that brought their provisions. Hither, therefore, bringing his army, then at leisure, he drew a great trench; and by turning the course of great part of the river, brought it to a convenient point on the shore where the water was deep enough to receive ships of considerable burden, and where there was a calm and easy opening to the sea. And this still retains the name it took from him.