By 100 BC, Rome's expanding boundaries were causing many difficulties. Discontentment was rife among lower classes. The military structure was disintegrating, too.

Economic tumult destabilized Rome. Huge Roman estates employed thousands of slaves captured abroad. One slave, Spartacus, led a slave revolt between 73 BC and 71 BC. Small farmers, who were often former soldiers, could not compete with the vast estates and often had to sell their land. They then became migrant laborers or joined the ranks of the urban poor.

Two brothers serving as tribunes, Tiberius and Gracchus, tried to aid the poor. Both were killed, and civil war followed their deaths.

The rise of popular generals was another danger. Generals recruited landless Romans, winning their loyalty. Those recruits became devoted to their general—not to Rome.

One of those popular generals was Julius Caesar. His men loved him and won a civil war that made Caesar dictator for life. Although Caesar would soon be assassinated, the Republic was finished.

The expansion of Roman territory during the era of the Republic made Rome a huge power and allowed it to take control of vast areas of land surrounding the Mediterranean.  However, the expansion also led to stresses that destroyed the Republic and helped turn it into an empire.

During the era of the Republic, Rome came to dominate its area of the world.  It defeated its major rivals, most notably Carthage.  It also took control of areas as far as Syria in the east and what is now France in the west.  This made Rome the greatest power of its time.

This expansion, however, helped lead to the fall of the Republic.  The stresses of war made it very difficult for the Senate to effectively rule.  This was exacerbated by the fact that the Senate was now required to rule a much greater amount of territory.

In these ways, the expansion contributed to the greatness and power of Rome, but it also helped lead to the collapse of the Republic.