* The rise of powerful military leaders, such as Gaius Marius and Sulla, who used their armies to gain political power.
* The expansion of the Roman Empire, which led to increased wealth and inequality, as well as increased tensions with other nations.
* The decline of traditional Roman values, such as civic duty and respect for the law, which led to increased corruption and political instability.
* The rise of the populares, a political faction that advocated for increased power for the common people, which led to conflict with the optimates, a faction that advocated for the preservation of the traditional Roman aristocracy.
The first century BC saw a number of political changes that contributed to the end of the Roman Republic. These changes include:
* The passage of the Lex Gabinia, which granted Pompey the Great extraordinary powers to fight the pirates who were disrupting trade in the Mediterranean Sea. This set a precedent for granting excessive power to military leaders.
* The Social War, which was a conflict between Rome and its Italian allies over the issue of citizenship. The war resulted in the Roman citizenship being granted to all Italians, which increased the number of voters and made the Roman political system more unwieldy.
* The First Triumvirate, which was an alliance between Pompey, Crassus, and Julius Caesar. This alliance was able to dominate Roman politics for several years and weakened the traditional republican institutions.
* The assassination of Julius Caesar, which led to a civil war between Caesar's supporters and his opponents. The war resulted in the victory of Caesar's supporters and the establishment of the Roman Empire.
These political changes, combined with the underlying causes of the downfall, led to the end of the Roman Republic and the establishment of the Roman Empire.