What are the literary devices in this poem?

Definitely imagery. Personification: "Justice that reddens the sky with her terrors...". Irony, when the talk about thousands have died for it, millions defend it/Emblem of justice and mercy to all. Definitely allusion when they talk about "Drifted our Ark o'er the desolate seas" (Noah, trying to create a perfect, new world. Think about what that means to the poem's subject). You can also talk about the author's sarcastic diction, especially in the last stanza.