Arriving in Alexandria in October 48 BCE and seeking initially to apprehend Pompey, his enemy in the civil war, Caesar found that Pompey had been assassinated by Ptolemy XIII's men. Caesar's financial demands and high-handedness then triggered a conflict which put him under siege in Alexandria's palace quarter. Only after external intervention from a Roman client state were Caesar's forces relieved. In the aftermath of Caesar's victory at the Battle of the Nile and Ptolemy XIII's death, Caesar installed his mistress Cleopatra as Egyptian queen, with her younger brother as co-monarch.