Just wondering

It's from Henry Wadsworth Longfellow's poem, "Paul Revere's Ride".

It was to alert the patriots of how the British troops were approaching. "One if by land, two if by sea." Lanterns were to be hung in the steeple of the Old North Church in Boston to alert the troops across the river.

Possibly apocryphal.

I'm well-versed in history outside "National Treasure" and I too wondered how the phrase related to the movie. It doesn't fit as a title.

I like the title- it's cute. It sounds better than One If By Land. Besides, there were 2 of them. Denis and Sandra and they did come by sea since they had to take a ferry to the island. Plus that other person pointed out that the thief in the end was British...