Rhetorical poetry in the U.S. becomes common during periods of social unrest and comes from poets standing (for the duration of the poem) for some sort of movement or viewpoint. I am a rhetorical poet. Usually in school we say "Oh it's political poetry, we don't like that." We are taught to say that there are three kinds of poetry: Lyric, narrative and epic. They forgot "rhetorical." Because we don't name rhetorical poetry, we can't see it, although when you read or teach Langston Hughes' "Mother to Son," or Robert Pinsky's "The Shirt," a rhetorical poem is what you've got. It's there but unnamed. It's like eating grilled cheese and a pickle for lunch and not realizing it was a vegetarian meal.
Rhetorical poetry is not simply writing a poem about the cause of the month. Carolyn Forche said, "To become a political poet, change your obsessions." You have to have something to say, feel it deeply, and take a stand on an issue. It helps if you're a good writer. It helps if you're part of a "we." "We" makes a poem political.
Here are some of my favorite knockout books of rhetorical poetry:
The Country Between Us, Carolyn Forche (about the U.S. in El Salvador; a highly honored book for good reason)
Power Politics, Margaret Atwood (sexual politics)
Here, Bullet, by Brian Turner (by U.S. soldier back from Iraq; Publisher's Weekly review begins, "The verse in this book is not good, but....timely"; sorry, PW: It's good.)
"A Woman is Talking to Death," by Judy Grahn (a single, powerful long poem, one of the great underground poems; collected in the book The Work of a Common Woman)
Crime Against Nature, Minnie Bruce Pratt (about how the poet lost custody of her sons because she's a lesbian; a book that richly deserved the award it won)
Dangerous Life, Lucia Perillo (about the threat of violence in women's lives)
Selected Poems of Wilfred Owen (soldier killed in World War I)
And many, many more. Yes, such poems have lyric and narrative elements. But they're also rhetorical poems. Don't leave home without them!