Final answer:
Franklin D. Roosevelt used repetition and other rhetorical devices in his 'Day of Infamy' speech to underscore the calculated nature of the Japanese attacks and to rally support for U.S. involvement in World War II.
Step-by-step explanation:
President Franklin D. Roosevelt's 'Day of Infamy' speech used rhetoric to engage the United States in World War II after Japan's attack on Pearl Harbor. In his speech, he uses strategic rhetorical choices to advance his purpose, such as suggesting the calculated and secret nature of the attacks and appealing to a sense of divine justice. One prominent rhetorical device Roosevelt employed was repetition, wherein he reiterated certain phrases to emphasize the coordinated nature of the Japanese attacks against American territories, instilling the message of a significant threat requiring a unified response.