Shelley opens by taking something away. "Thou wert not, Cassius, and thou couldst not be, / Last of the Romans": the phrase is the epitaph Brutus speaks over Cassius in Shakespeare's *Julius Caesar*, and the speaker now refuses it to him. The point is not to insult Cassius but to clear space for a rival claimant, Otho. The name fits the Roman emperor Otho, remembered for ending his own life, and the closing lines about a death "in his own blood" suggest that is the man meant. The poem never explains this, though. It simply assumes that its reader will follow the argument.
That argument is the real subject. The first stanza is one long, winding sentence in which Cassius's memory "claim[s] / From Brutus his own glory," and an unnamed figure, who "dared make the foul tyrant quail / Amid his cowering senate" by invoking Cassius's name, is brought in as another heroic voice. Both are called great, and then the sentence turns on "though" and arrives at its paradox: "it will avail / To thine own fame that Otho's should not fail." Honouring Otho, the speaker insists, takes nothing from Cassius. Fame here is not a limited stock, and one hero's share does not shrink another's. The repeated rhymes of "fame," "name" and "claim" make the stanza feel almost obsessed with reputation, as if the sound itself were arguing the case.
The form is tight. Each of the two stanzas has eight lines of iambic pentameter, rhymed ABABCBCC, so the second stanza copies the first exactly. The pattern resembles ottava rima, but the closing run of three rhymes (avail, fail; bring, offering, spring) is its own. That last rhyme pair in each stanza lands like a verdict. Dashes and mid-line pauses give the voice an orator's stop-and-start energy, and enjambment pushes the sense across line breaks, as in "on thee / Rests the full splendour of his sacred fame." The verse sounds like someone addressing the dead directly. "Thou" and "thee" make Cassius a listener, and the poem even imagines his reaction: he "wouldst, if thou couldst feel, / Abjure such envious fame." The conditional is neat, because a dead man cannot feel envy, and the speaker uses that to dismiss any rivalry between the two.
The second stanza turns from argument to image, and the images are sharp. Otho "sanctified his country's steel." Steel is a hard, practical word for a weapon, and "sanctified" is a religious one. The line makes the blade holy by joining the two. Then comes the poem's boldest phrase: he was "at once the tyrant and tyrannicide." Judging by this line, the speaker sees Otho as holding the power a tyrant holds while also delivering the death a tyrannicide delivers, both in a single act and a single body. The sentence ends with "in his own blood," where the violence turns inward.
The closing lines soften the tone. The deed would "bring / Tears from all men," yet it is "full of gentle pride, / Such pride as from impetuous love may spring." "Gentle pride" and "impetuous love" are both pairings of opposites, and they suggest a feeling that is calm and fierce at once. The last line gives love a will of its own: it "will not be refused its offering." The vocabulary has been moving steadily toward ritual, through "sacred fame," "sanctified" and now "offering," so the death reads less as a defeat than as a gift laid on an altar.
What makes the poem worth reading is how much it packs into sixteen lines. It takes a famous title, "last of the Romans," and quietly questions who deserves it. It asks whether glory must be shared out or can simply be added to. And it holds up a self-inflicted death as an act of patriotic love, a position readers may well want to challenge. The syntax is demanding, and you often have to reread to find who is being praised and who is being corrected. But that effort suits a poem about judging greatness carefully rather than taking inherited reputations on trust.