Tiberius and Gaius Gracchi were the scions of an old and successful aristocratic family. As Tribunes of the Plebs, they pushed for reforms that marked them as betrayers of their class and ultimately led to both of their deaths, ten years apart from their respective tribunates.
The great reforms they sought to carry out were the redistribution of land from the wealthy, who owned increasingly more of it, to the ever-increasing urban and rural poor. The roots of this problem stemmed from the Roman law which stated that only land-owning citizens were allowed to participate in war. While this law had rarely before caused strain on the small share farmers fighting short campaigns on the Italian peninsula, it most certainly did during the long Punic wars. Veterans fighting for ten years in the Third Punic War returned to find that their small farms had failed in their absence and had been bought up by a new class of wealthy landowners. Now landless farmers flooded the city of Rome, creating an even larger population of urban poor.
Seeing this, Tiberius, himself a great hero of the Third Punic War, sought as Tribune to address the problem by redistributing land, in some ways an attempt to take Rome back to a society of self-sufficient citizen farmers. The first land reform commission, staffed by himself; his brother, Gaius; and their father-in-law, rankled the Senatorial class, many of whom were the very people who would lose their newly acquired lands.
The methods by which both brothers attempted their reforms further upturned the political apple cart. First, the veto power of the Tribunate, in which the Tribune could veto the decisions of the Senate, was used as never before. Second, the Gracchi, after it became clear that the Senate would not back their reforms, attempted to leverage popular support by bypassing the Senate and attempting to pass laws directly through the Plebian council via the invocation of the Hortensian Law (Lex Hortensia). The Lex Hortensia was a law, passed a few centuries before the Gracchi, that allowed the Plebian council to pass laws without the approval of the Senate, when invoked by the Tribune. Due to custom and the typical coziness between the Tribunes and the Senate, it had never been invoked, and the use of it by the Gracchi was viewed unfavorably by the Senate.
In 132 B.C., Tiberius and 300 of his supporters were clubbed to death by a group of Senators and their quickly arrayed force, using the very pieces of furniture in the Senate hall. Ten years later as Tribune, pursuing more aggressive reforms than his brother before him, Gaius was chased out of town and likely committed suicide.
Some of Tiberius's reforms were adopted by the Senators who killed him, while Gaius's grain distribution scheme was kept on. However, the reforms that were adopted were too little too late in slowing down the increasingly unequal distribution of wealth and property that was to become one of the hallmarks and forces of instability in the later Roman Republic and Empire. The Gracchi brothers' extraordinary actions in service of the regular people of Rome could be said to serve as previews of the conflict that would continue to challenge the structure of the Roman Republic, while their efforts would resonate beyond their lives with those who seek to build equitable and just societies.