Answer:
To suggest that history will remember the date because of the tragic events.
Step-by-step explanation:
The word 'infamy' connotes the widespread belief that something or deed is bad or evil.
President Roosevelt begins his speech with the comment that December 7, 1941, will live in infamy, suggests that history will never forgets the bad occurrences that occasion on the said day.
Today, not only the remark by President Roosevelt true, History students now knows the import of the tragic events that occurred on the day. Hence, will live in infamy - as a dreaded day, is correct in retrospect.