Someone is dying, and the poem follows them through their last moments. The poem never names the person or says how they came to this point, so the details stay open. The imagery of a "bunker," "holes," and "scratch" hints at some kind of battle or injury, but that is an inference from the wording, not something the poem states.
The opening is the most frightened part. A dying lantern clutched tight stands for the last of a life, and the night keeps closing in. By the middle, the speaker's tone turns quieter, almost resigned. They ask what all the holding on was for, wonder if it was just to feel the wind and see the stars again, and then admit it hardly matters now. The repeated lines, "no more, no more" and "the darkness comes," work like a slow heartbeat.
The ending surprises us: the fear is gone, replaced by a smile. The mood is sad but gentle, ending in acceptance rather than terror.