Final answer:
The First Triumvirate, formed in 60 BCE, consisted of Julius Caesar, Pompey, and Crassus, who were united against the Senate's optimates and motivated by personal ambitions. Following Crassus's death and Caesar's military triumphs, the Triumvirate disintegrated, leading to civil wars.
Step-by-step explanation:
The First Triumvirate was formed in 60 BCE as a political alliance between Julius Caesar, Pompey, and Crassus. This alliance was largely due to their mutual opposition to the optimates in the Roman Senate, who worked against their political interests. The individual desires of the Triumvirs for military command and political influence were also driving factors behind the formation of this alliance. After Julius Caesar's consulship in 60 BCE, he took command of Roman troops in Gaul, achieving great military successes which in turn incited jealousy from Pompey and Crassus. Crassus's attempt to match Caesar's conquests by invading the Parthian Kingdom ended in disaster and his death. Ultimately, the tensions and ambitions within the Triumvirate led to its dissolution and the initiation of civil wars.