Hanging from the beam,
Slowly swaying (such the law),
The opening lines of the poem are graphic, showing the image of a body that has just been hung. The parenthetical mention of the law indicates that the hanging was not mob violence; it was sanctioned by statute. The intent of this parenthetical is to underscore a paradox: the state just killed a man for killing men. The man hanging killed in an attempt to abolish slavery, and the state killed him to preserve the perilous status of legal barbarity.
Gaunt the shadow on your green,
Shenandoah!
The exclamation point after Shenandoah is a meaningful choice of punctuation. The body is hanging in Virginia and the poet wants the reader to recognize the importance of the location. The law that supported the legal hanging is the law of the state of Virginia. Virginia is where the law also makes it permissible to own other human beings as property. The poem also references the Shenandoah Valley because it was the legal boundary between slave states and free states. In the events of the poem, the valley’s verdant green has a shadow casting a pall over it, the legal hanging of a man the poet views as a portent, not a criminal.
The cut is on the crown
This quote references the wound John Brown sustained on his head during his capture. However, this line is also a metaphorical reference to governance. Although America did not have a monarch wearing a crown, this line employs a metonymic device that applies the general understanding of “crown” as a head of state to the government itself. The poem suggests there is a wound on the body politic. Thus, it is not just Brown who is being killed; his actions have inaugurated a chain of events that will do violence to the government itself—a "cut on the crown."
The meteor of the war.
The final line of the poem circles back to its title. The hanging of John Brown is seen—in retrospect—as a harbinger of the Civil War. Meteors have a long and ancient history of being viewed as portents of seismically significant events. Melville paints John Brown as a meteor streaming across the sky, flaring brightly and dying out, warning that if America did not address the evil of slavery, war would be inevitable.
