Marcus Antonius:Julius Caesar Act 3, scene 1, 270–275
And Caesar's spirit, raging for revenge,
With Ate by his side come hot from hell,
Shall in these confines with a monarch's voice
Cry "Havoc!" and let slip the dogs of war,
That this foul deed shall smell above the earth
With carrion men, groaning for burial.
Since Julius Caesar's assassination, his right-hand man Marc Antony has had to resort to veiled ironies in putting his own case to the public [see FRIENDS, ROMANS, COUNTRYMEN, LEND ME YOUR EARS]. Privately, he rages. As he prepares to strike back at the assassins, Antony invokes Caesar's spirit and Ate, goddess of ruin and strife. Hot from hell—the pagan catch-all for both the blessed and the damned—Caesar and Ate will charge in with dogs of war, visiting havoc on the conspirators. (The dogs in a sense personify—or "caninify"—war.) At least, these are Antony's superheated imaginings; the final destruction of Brutus and Cassius will have more to do with their bad consciences and tactical errors.
"Cry 'Havoc,'" which also surfaces in King John, is derived from the Old French "crier havot"—to send out the signal to begin pillaging. Latter-day usage of "cry havoc" follows Shakespeare in the figurative sense of "call down destruction."