The correct interpretation of the lines from "Paul Revere's Ride" is:
The dark windows suggest the deaths that will take place in the battles the next morning.
This interpretation aligns with the imagery of the "blank and bare" windows that seem to gaze at Paul Revere "with a spectral glare," indicating a sense of foreboding and foreshadowing the violence and bloodshed that will occur as a result of his ride and the impending conflict.