Why did Pompey marry Julia, Julius Caesar’s daughter?

Pompey the Great married Julia, the daughter of Julius Caesar, primarily to solidify the political alliance known as the "First Triumvirate" between himself, Caesar, and Marcus Licinius Crassus.12

This marriage served as a crucial bond to ensure the continued solidarity of the three men, who sought to advance their careers and secure their political objectives despite opposition from the Roman Senate. For Pompey, Caesar functioned as a necessary instrument to help secure his goals, such as land for his discharged troops, while the alliance allowed the three dynasts to effectively monopolize military and political power in Rome. The marriage remained the strongest link between Pompey and Caesar until Julia’s death in 54 BCE, which ultimately contributed to the collapse of their partnership.132