Which patterns can you identify in the poem?

"O Captain! My Captain!" is the only Walt Whitman poem that has a regular meter and rhyme scheme. Often hailed as "the father of free verse," Whitman tended to write his poems without following any kind of ordered poetic form. However, "O Captain! My Captain!" is organized into three eight-line stanzas, each with an AABBCDED rhyme scheme. Each stanza closes with the words "fallen cold and dead," and the first four lines of each stanza are longer than the last four lines. Because this poem is an elegy to the dead, the more traditional format adds to its solemnity. Additionally, the regular meter is reminiscent of a soldier marching across the battlefield, which is fitting for a poem that commemorates the end of the Civil War.