The pivotal moments in the life of Cleopatra that defined her reign include her alliances and relationships with powerful Roman leaders. Her romantic engagement with Julius Caesar solidified her power and influence in Egypt, while her subsequent liaison with Mark Antony was strategically aimed at bolstering Egypt against Rome's expansion. Cleopatra's political acumen was evident as she navigated the complexities of Roman politics, attempting to protect her kingdom. Her reign ended tragically after her defeat by Octavian, marking a significant transition in Egyptian history and culminating in the end of the Ptolemaic dynasty.