The Gracchi brothers, while championing causes for the common people, were themselves members of the highest Patrician order of Rome. Their father was a consul and their mother was of the distinguished Scipio family. Tiberius started his political career under the wings of C. Scipio Amelianus but later was to be opposed by the powerful Senatorial elite of which he was originally a member.
As a quaestor in Spain, Gracchus got his first bitter taste of factional politics. The Roman army had suffered miserably against the Celtic tribes and he proposed a treaty that was written to spare the lives of up to 20,000 Roman soldiers. The treaty was firmly rejected in Rome, because passage would've been akin to admitting defeat. This terribly disappointing incident marked Tiberius' break from the optimates and the beginning of his opposition to the elite authority as a supporter of the populares movement.
The Populares party was convinced of the need for reform in many facets of Roman society. Some members, perhaps Tiberius included, simply liked to oppose the established authority, and he may have been used in his early days by the more prominent members. Whether Tiberius himself was sincere in his reforms to benefit the common man is impossible to ascertain, but regardless, he developed into an icon of equality for all people of Rome. Badly tarnished by the rejection of his treaty, Tiberius took up the challenge of reform with a zeal previously un-encountered in the Roman forum.
Election as a Tribune of the Plebs in 133 BC was the beginning of his fight for reform. He likely had little intention to cause the sort of upheaval that followed, as economic security and stability was a real concern. The Plebeians had long struggled for social equality and a magisterial office in which to voice their concerns. The introduction of slave labor in mass quantities and loss of plebeian farms from the previous wars left the Italian farmers in dire straights.
Patrician and upper Equestrian families acquired vast stretches of new lands in the recent wars, while the Plebeians gained none. In fact many farms were lost simply because men were killed or wounded in the wars and unable to work their lands. According to Roman law, land gained in such a manner was to be shared equally among the masses, and not simply distributed to the Patricians. The inability to compete with the huge slave labor farms of the wealthy certainly played a part in Plebeian dissatisfaction.
As Tribune, Tiberius now had the power and position to begin the process of change. He introduced legislation, a concilium plebes, for a creation of land allotments to the Plebes out of the public lands won in the Punic Wars. In this case the bill may have been in complete good faith and intentions. It stated that those currently living on the land would be restricted to the legal limit of ownership (500 acres plus 250 acres each per son, limited by 2 sons.) and would be compensated by being granted a hereditary rent-free lease. This would restore land ownership to more Plebes and satisfy a variety of social needs. The ranks of land-owning citizens would be increased, making more people eligible for service in the legions, while putting more people to work and balancing the social scale, if even by a small amount.
Gracchus' bill, as sound and perfectly legal as it may have been, was immediately opposed by the Senate. Not only would the bill have a direct effect on the benefits they themselves could receive, but Gracchus flagrantly opposed them by taking the bill directly to the citizen assemblies, rather than to the Senate for discussion and debate first, as was customary. Octavius, the other Tribune for that year, and apparently as a pawn of the Senate, used veto powers to undermine this reform land bill and Tiberius was stymied. In opposition, Tiberius raised the ante by disrupting every form of legislation and governing of any sort throughout his term as Tribune. He used his own veto right to put down every proposed law or bill effectively shutting down the government until his own bill could be dealt with.
At the next citizen assembly, he was sure that he had taught a lesson to the opposition and that his bill would pass without incident. Octavius, however, vetoed the Agrarian bill once again. Attempts to have Octavius physically removed from the Tribunate in order to allow passage of the bill by popular vote all failed, but the assembly voted for the bill anyway despite Octavius' veto. The bill passed into law, as the Senate had little choice, regardless of the illegally ignored veto attempt. Perhaps facing open rebellion from the mob, they allowed its passage but relations with Tiberius were badly strained.
Upon the bill's approval, three men were commissioned to oversee its institution. Tiberius, his brother Gaius Gracchus and Appius Claudius Pulcher, a leading Senator and Tiberius' father-in-law. As many as 75,000 small farms may have been created with the bill and handed to small farmers. There was a noticeable improvement in social conditions, but the plan proved an expensive project to implement. Money allotted to oversee the introduction of the law was running low and Tiberius proposed to take money from the rich and newly acquired land of Pergamum.
The Senate once again opposed the concept, but was not willing to risk Tiberius taking the matter before the Plebes. Reluctantly, this issue was passed, and Gracchus' continued direct challenges to Senatorial authority was backing himself into a corner. He used the people as his mob, threatening the Senate into supporting his bills. All the while, Tiberius was immune from retaliation as long as maintained his position as Tribune (which was considered sancrosect or rendered him immune from legal prosecution and physical harm).
Hostility between the 2 factions continued and the relationship deteriorated. As the year of his tribunal powers neared a close, Gracchus was in real danger of court trial or even assassination if he couldn't get re-elected as Tribune. However, the law stated that no man could stand for election without an interval period without holding office (this essentially was a check and balance preventing the abuse of power if office holders could face immediate prosecution following their terms of duty). Therefore it was illegal for Tiberius to run for election again. Tiberius, with the popularity among the people behind him, ignored Senatorial objections and carried forward with his election campaign anyway.
Once again, the Senate was powerless to stop the rising star of the popular Tiberius Gracchus. Without recourse and entirely enraged by Tiberius' constant mocking of Roman law and tradition, the Senators took up arms against him. Led by Tiberius' own cousin, Scipio Nasica, a group of armed Senators and supporters charged into a 'populares' campaign rally to break it up. In the ordeal Tiberius was clubbed to death (certainly after being marked as a target), thus ending his short but tumultuous political career.
In the aftermath, Scipio Aemilianus (who was much beloved for his service in the final destruction of Carthage) was called in to restore order and the political situation slowly settled down. As it turned out, however, the political fever introduced by Tiberius Gracchus would pale in comparison to that of his younger brother Gaius Gracchus, just a few years later.