The poem is a few lines long, but it packs in a strange, heavy image of evening. Dusk is compared to a mole, a creature that lives underground, and this mole is "full of land" and "done in with war." The comparison suggests the end of the day feels crammed with earth, exhausted, and beaten down, as if the light has been burrowing through something violent and is finally giving out.
The last lines shift to a quieter, bleaker thought. The speaker wonders how much the day will "rust" once it passes into "the country of night." Rust implies slow decay, so the day seems to be something metal left to corrode in the dark. Night becomes a whole territory where finished days are stored and wear away.
The speaker's feeling seems to be tired sadness, maybe a sense of loss. The war reference is brief, so the poem leaves its source open, but the mood is clear: dim, heavy, and resigned, with dusk as a moment of ending.