The poem is written in alexandrines: a verse line consisting of six iambic feet, or 12 syllables. An iamb is a poetic foot consisting of an unstressed syllable followed by a stressed syllable. An alexandrine is also known as an iambic hexameter. Line 2 is a good example of an alexandrine: “And yawning sentries mumble, ‘Wirers going out,’” as is Line 11, “Young Hughes was badly hit; I heard him carried away.” Both these lines also contain a pause, called a caesura, in the middle of the line. This is a characteristic feature of the Alexandrine line. The caesura can be any form of punctuation, such as a comma, colon, period, or dash. In this poem, all but two of the alexandrine lines (Lines 4 and 13) contain caesuras.

For the sake of variety and to avoid monotony, the poet occasionally varies the meter. In Line 5, “Black forms,” the phrase that follows the caesura, is not an iamb but a spondee, in which both syllables are stressed. The following line, Line 6, begins with a spondee, “Stock-still,” as does Line 7, “Stride hither” (first two syllables) and Line 10, “Gleams desolate” and “night's misery” (in both examples, the first two syllables form a spondee).