that's because it's part of a famous poem written by henry wadsworth longfellow.it begins with the words... some people believe that longfellow's poem is about as accurate as a colonial musket with a bent barrel. >> well, it is a beautiful poem, but it's horrible history. >> and he should know. bob damon is a historian. he explained to me some of the inaccuracies in longfellow's poem. let's start with its most famous line. >> "one if by land..." >> "...and two if by sea." >> it's wrong. the british were never going by sea. so it was a river, not a sea? >> it was definitely a river, not a sea. and as a matter of fact, we might even say it was the back bay and the charles river, as opposed to a sea. >> whis accurate is that the signal was given from this boston church, called old north church. the poem goes on to say that revere was across the river waiting for the signal. >> "and i on the opposite shore will be, ready to ride and spread the alarm through every middlesex village and farm." >> and, in fact, he wnot on the other side of the charles river. he was being