The social and political landscape of the Roman world was about to undergo an abrupt transformation in the Late Republic. The emergence, and eventual assassination of the Gracchus brothers, Tiberius and Gaius, is often considered the first major step towards the fall of the Roman Republic.
While Roman class and social affairs had for centuries consisted of machinations by various individuals to get their way (such as the Plebs withdrawal from Rome in the early Republic), the activities of the Gracchi completely altered the state of Roman politics.
The careers of these two men were marked by riots, murder, and ultimately, outright manipulation of the common population to achieve their goals. This political behavior would become increasingly more prominent in the 100 years from their time, through to Caesar and the eventual rise of Augustus.
The tremendous growth of the Empire, through both acquisition of land, slaves, and various citizen classes led to a fundamental divide in the Roman political system. On one side of the divide, the patrician and wealthy, long-standing equestrian families developed into a faction known as the optimates (though there were certainly exceptions). Essentially the conservative party, these aristocrats were the old and powerful families of Rome. Their goal was the preservation of the Roman state, in its then current form, where these families reaped the benefits of Roman expansion and the senate maintained controlling power of the system. Roman strength, in their opinions, resided with their ability to lead and the results of that leadership would help all of Rome.
By contrast, a new faction began to gain power as some of the members of these powerful families began to take up the causes of the less fortunate common masses. Manipulating the 'head count' or the 'mob' with popular ideas was a powerful political tool, but none before had used it as effectively as the Gracchi. The Populares party took root in this Late Republican period, and the 'causes of the common man' (or political ambition guised by such causes) became a constant factor in the political wrangling of the capital.
From 137 to 121 BC, Tiberius, and then Gaius Gracchus, stood at the center of this turmoil. The recent conquests had opened many doors to new found wealth, but the rapid pace of such expansion opened more doors to corruption and mismanagement. The lack of new recruits from among the landowning class was beginning to take its toll. Small farms were slowly driven into extinction as the wealthy bought up land and resources for vast estates. Laws preventing the Legions from taking the landless as recruits were certainly an issue. These displaced Roman's had no farms and no opportunities to regain their status through military service. Governing all the new provinces was a strain at best, without a large recruiting base of small landowners.
Meanwhile, the Optimates' land base continued to grow and the agrarian laws of the time were certainly written in their favor. Slaves imported with the conquests replaced the Italian worker and the small farmer. Thousands of landless and jobless Romans were idle in the city, with little hope for relief. Food supplies dwindled as less farms were worked. Social debt and overwhelming corruption was rampant throughout the entire society. Italian allies were feeling more and more disenfranchised, as they had these same issues without even the right to vote in the citizen assemblies. The stability of Rome was badly fractured, just as it started to grow into an empire.
Tiberius and Gaius Gracchus saw an opportunity not only to achieve their own political power, but to stabilize the inequality through reform and new laws benefiting the common people. Reasonable and noble concepts on the surface, however, were underlying with their own contempt for the Senate and optimate party. What could be seen on one side as an attempt to rectify a dangerous and debilitating social system was viewed on the other as nothing more than a power grab and a flagrant attack on the Republican institutional ideas of the time.
One-upmanship was countered with arguments and these countered with physical force. As the results at stake grew, so did the egos of the individual players. The goal of the betterment of society as a whole was lost, and victory became the only objective. As ambition and personal motivation became the predominant theme of the Late Republic, the social fabric that long held Rome together, against all odds, was being torn apart.