Marius was a young man when Tiberius Gracchus rose to power, and subsequently was murdered, and served in Numatia, North Central Spain during the second of the Numantine Wars. He must have carried himself well because none other Scipio Aemilianus, though you may better know him as Scipio Africanus due his victory over Carthage in the final Punic war that propelled Rome into the Mediterranean's only super power, patted young Marius on the shoulder when asked who would best succeed him as Rome's premiere general.
From the end of the Numantine Wars in 133 B.C to 120 B.C when he was elected tribune of the people, with the support of the leading conservative leader of Rome Quintus Caecilius Metellus, little is known. He ran for a local office, and lost, and then ran as a Quaestor in Rome, and lost again, however, he must have paid attention to power gained by the Gracchi brothers due to their populism, because even though he was supported by a conservative for the tribunate, he adopted a populist, which must have greatly contributed to the enmity between him and Metellus during later years. The enmity was enough to prevent Marius from aedilship and his narrow win for the praetorship in 116 B.C, and the subsequent charges of electoral corruption after his election.
His stint as praetor, Rome's equivalent to a court judge, was uneventful and in 114 B.C he was sent to Lusitania, modern day southern Portugal, to govern and clear out the highway robbers that had become a minor nuisance in the area. I assume Rome considered it a minor nuisance because even though the robbers were enough of a nuisance to warrant a pro-praetor to muster military forces, his victory wasn't grand enough to warrant a triumph.
So far, Marius' career wasn't spectacular, though his marriage to the aunt of Julius Caesar of the Julii family indicates that Marius had become respectfully wealthy and influential in Roman politics. What made Marius was Jurgutha the King of Numidia, modern day northern Algeria, and the military campaigns against him. Though it was Sulla, future rival to Marius, who captured Jurgutha, the war in Numidia would begin Marius rise to the top of Romes political elite.
The ill-will between Metellus, now Consul, and Marius must have dissipated, was overstated, or Metellus simply saw Marius for the competent military leader he was despite their rivalry, and selected Marius as his legate, an equivalent to a division X.O, for his campaign against Jurgutha. Marius used this appointment to boost his political career as he ran for the position of consul the next year, however, he did so without the support of Metellus. Some historians think it was because Marius was a novus homo (new man) and I concur with this assessment. Metellus had advised Marius to wait until Metellus' son was of age, and run with him for the consulship, however, Pius was 29 years old and would be ineligible to run for the office for another 13 years, Marius was already 49, and be 62 years old by then.
Marius campaign would signal the final break with Metellus as Marius would use Metellus' inability to stop Jurgutha as a reason why he should be elected consul and lead the legions; as well as railing against the corruption of the nobility. This strategy, which would resemble the class warfare demagoguery we see today, had served the Gracchi brothers well, and Marius had learned well. While Marius successfully won the consulship, a major feat considering his status as a new man, the Senate tried to circumvent him by using the Lex Sempronia against him.
The Lex Sempronia, the law passed by Tiberius Gracchus, among many things, dictated which provinces would be designated as consular provinces for the following year prior to the elections of that year. The Senate used the law to their advantage by deciding not to make on of the provinces where the war was being fought against Jurgutha into a consular province, and to further rub salt in Marius wounds, to prorogue Metellus imperium in those provinces. This meant that even if Marius was elected consul, and it looked likely, he would not be able to command the legions against Jurgutha.
This move, while perfectly legal, was incredibly underhanded politically, though underhandedness had been the trait of the senate for many decades now, and probably contributed to many of the rash actions that Marius would talk in his final years. However, the senate failed in the endeavours, because Marius not only was a military genius, but also a political one as well. He used a ploy that had been successfully used for the war against Eumenes III in 131 B.C At that time a tribune had passed a law authorizing the popular election for the commander, it wasn't without precedent, as this had also been done during the second Punic war, so it was not illegal, but it was unusual. Marius successfully got a tribune to push the proposal forward, and the plebeian council to elect him as the commander of the legions against Jurgutha. There was nothing the Senate could do. This election would prove to have profound impacts of Rome's military and Rome herself.
Marius was an able general, and well loved by his men, he ate with them, bonded with them, and proved himself a soldiers soldier, unlike the many aristocratic men who often held the position of legate, tribune, or consul. Marius understood that the way the military was organized was killing the republic. First off Rome's legions were an entirely volunteer force of Roman property owners, the middle class of Rome, and the time spent fighting was a sacrifice for these men. While they were gone only their wives and children could tend to their land, and sometimes, not even then. The never ending wars were slowly bankrupting the middle class as their ploughs would go fallow, and they would be unable to sell enough produce to pay for their land. Too add insult to injury, their land would be repossessed and then bought up by one of the wealthy patrician families of Rome, or other Latin city. This was contributing greatly to the violent populism that was becoming more prevalent in Rome and threatened the Republic.
The other issue is that these wars were killing Rome demographically as well. The able bodied men of Rome were going off to war, and as in all wars, sometimes getting killed. While Rome was very successful in waging war, and because of it suffering drastically fewer casualties than their enemies, the long periods away from home, and the deaths that did occur, resulted in fewer infants being would born. As I have said before, demographics is destiny, and the lack of infants being born, for the middle class at least meant that there were eligible men to fill the ranks down the road. This had been going on for some time and it was reaching a breaking point. It was becoming increasingly more difficult for the Romans to muster the forces they needed, which meant they were increasingly relying on their allies; and that helped contribute to growing allied resentment that would later lead to the Social War.
Marius may have seen that particular threat, though it is more likely he was worried about incursions from the barbarians to the north of the Italian Alps, and made some drastic decisions that would fundamentally alter Romes military, what we now know as the Marian Reforms. He relaxed the requirements that would make a man eligible for military service by removing the stipulation that a man must own land and allowing men regardless of their social class enlist.
Moreover, Marius eliminated the levy, and instead recruited individuals to fill his ranks. This would have a momentous change on Rome, as rather than having a conscripted service of individuals who would serve for a short period, the ranks of the legions would be filled with career soldiers. There were many benefits to Marius' move such as bolstering the ranks of the legions and increasing Romanization of conquered provinces, however, there were numerous pitfalls that would become painfully evident during the civil war years. The legions had formerly been filled by the ranks of the middle class who served the republic out of duty, and once the campaign was over, would return home to their homes or newly won lands. Now the legions would be filled with the unemployed and poorer classes who would fight for coin, and more importantly, whoever provided said coin.
While the long term implications of such a decision would become painfully evident during the first civil war between Marius and his supporters against Sulla, who served as a Quaestor for Marius, later in the short term Marius provided the shot in the arm the legions desperately needed and a temporary outlet for the mounting social unrest that rampant unemployment was having on Rome.
Marius was unsuccessful in completely defeating or capturing Jurgatha, Sulla would have that honor, Marius, as consul receive the credit and this credit would help propel him to an unprecedented consecutive term as consul. Much like Tiberius' and Gaius' moves towards a consecutive tribunalship, Marius' second term was unprecedented, and unconstitutional. But unlike the Gracchi brothers, Marius did not actively campaign. Marius was elected in absentia, he was still off campaigning, and this meant that the Senatorial body violated it's own constitution due to issues with the barbarians to the north.
This is an important event because even though Marius may have been the only consul able to handle Cimbri, who had defeated two Roman lead armies against them, there were well established ways to extend the military command of Marius, specifically the prorogue, but the Senate instead opted to reelect the man as consul. This signifies how far the Senate has fallen, they set aside their laws for expediency, and this resulted in Marius being elected consul a total of 6 times, something never before seen in the republic, and signifies what is to come in the future.
There is a lot more to write about Marius, after all he is the destroyer of the republic, however, this ties into the next post, the rise of the Sulla, who becomes dictator of Rome largely due to Marius. After the Social war, the rivalry between the two men will flare into open warfare, and so too, does the decline of Rome accelerate.