One if by land, and two if by sea;
And I on the opposite shore will be,
Ready to ride and spread the alarm
Through every Middlesex village and farm

Those words, by Henry Wadsworth Longfellow, have been memorized by countless people learning about the revolutionary era of the United States.  The poem refers to hanging a lantern (or lanterns) in the belfry of the Old North Church is Boston as a signal that the British were coming, and ...