The 372-line poem contains 91 stanzas, largely quatrains (a stanza of four lines of poetry). The poem’s aabb rhyme scheme repeats throughout the poem, though some stanzas have slant rhymes, which means the words are not exact rhymes.

Most lines have seven syllables, though some have eight, and each pair of syllables is a trochee, or a stressed syllable followed by an unstressed syllable. This meter is based on a popular ballad form of Shelley’s day.

The poem’s form is a ballad, which is a poem or song that narrates a story with short stanzas. Often ballads are passed orally as a part of folk culture. As a ballad, the poem also focuses on imagery that is both historically important and tragic. Shelley’s framing of his poem as a ballad also supports how he positions his subject as epic in nature, as if this event was the origin of a new England, like the mythical origins of Rome. Shelley’s characters, while ordinary people, are extraordinary in their actions in the face of an almost superhuman enemy. The ballad form allows Shelley to use this event as a rallying cry for radical reform.