Gaius Marius was the son of a small plebeian farmer near Arpinum. Contrary to popular belief, the Marius clan was influential locally, and maintained some limited client relationships with those in Rome. Of equestrian, but outside roots, Marius would find his early attempts to climb the Roman social and political ladder difficult at best. Using the Legion as his route to fame, fortune and power, he would become among the most influential men of his day, and the history of Rome. Ancient sources suggest that Marius was pre-destined, through the visions of a seer, to be Consul of Rome 7 times. Not only would this prove true, but he would eventually be hailed as the third founder of Rome, and its savior. Military glory and personal ambition drove Marius straight to the top of the Roman system, but perhaps even more importantly, the man and his legacy would have a profound impact on the life of his nephew, Gaius Julius Caesar.
As a youth Marius may have used his modest family influence to join the legions as a junior officer, or may have risen from the ranks. It is difficult to determine exactly, but it is known that he spent his early career in Hispania under Scipio Aemilianus, grandson of Scipio Africanus. Performing his duties admirably he quickly was promoted. By 123 BC, at the age of 34, the veteran officer was elected as quaestor and his political career was off the ground.
As a novus homo, or new man, Marius found the rise in the Roman cursus honorum a daunting challenge. It is certain that he used his old family client contacts and his military relations as a source of support. Among these contacts were the powerful Metelli family, and their early support was to prove to be a disaster for them. Just a few short years after his service as Quaestor, Marius was elected Tribune of the Plebes in 119 BC. In this position so soon after the political turmoil and murder of the Gracchi brothers (Gaius murdered 123 BC), Marius chose to follow the populares path make a name for himself under similar auspices. As Tribune, he would ensure the animosity of the conservative faction of the Senate, and the Metelli, by passing popular laws forbidding the inspection of ballot boxes. In do doing, he directly opposed the powerful elite, who used ballot inspection as a way to intimidate voters in the citizen assembly elections.
Immediately devoid of political support from the social elite, Marius was unsuccessful in several attempts to be elected as an aedile. His persistence, and disregard for his new man status made him several enemies, but he would persevere. In 115 BC, he was elected Praetor, but was bogged down by politically motivated challenges to his election. After a year of service in Rome, Marius was assigned the province of further Spain for his proprietorship. While a seemingly inglorious position, he served well, and his military experience played a significant role. Putting down several small revolts, and amassing a considerable personal fortune in Spanish mineral wealth in the process, Marius returned to Rome as a successful and perhaps more modest new man. Sensing the resistance, he put off any attempts to run for the next stage of Roman offices, the Consulship.
Perhaps his decision not to run for Consul, his amassing of personal wealth or other factors cooled the animosity between him and the optimate powers. In 110 BC, in taking advantage of the calmer political environment, Marius would make an arrangement that would send shock waves through his own life and Rome itself. The Caesar branch of the Julii family, as impeccably Roman and patrician as they could come, had completely fallen from political prominence and at this point, didn't have the personal wealth to change matters. Likely heavily influenced by Marius' money, as he was socially considered an uneducated, ill-mannered barbarian, a marriage was arranged between Julia Caesar and Gaius. Marius gained the benefit of entry into social and political circles that he would never have had, and the Julii were immediately re-established as a power player through the financing of political campaigns by Marius. As a result of this marriage and his apparant relaxed political motivations, the breach that existed between Marius and the Metelli was soon also healed. By 109 BC, the consul Quintus Caecilius Metellus Numidicus, would select Marius as a chief subordinate for his campaign against Jugurtha of Numidia.