Expository or not?

Yes. And no.
(What makes you think that expository writing has to be "dry and without figurative writing"?

There can be no "description" without selection and interpretation. Some would argue that the poetic genre adds to the interpretation. (Look at "The Charge of the Light Brigade" if you need an illustrative example).
http://en.wikipedia.org/wiki/The_Charge_of_the_Light_Brigade_(poem)

Good example, fresco. Almost all poetry based on historical events is expository in some sense of the word. That certainly doesn't detract from its lyrical wording. Nor does that lyricism make the subject matter less expository.

Wouldn't be prose if it were dry and without... And the line between prose and poesy is pretty thin... I would say that the Illiad was pretty expository, but what must be remembered with all forms of literature is the inability of people to tell the truth, first because they do not know it, and second, because what is truth is always changing, and no more so than in the telling of it which inevitably leaves out so much, and tells so little....

The historical is only background, the set, if you prefer, for the human and moral elements... To use my example, The Illiad is the Goddess putting words in the mouth of Homer about the wrath of Achilles, and the action of the play is so much the result of those human choices that made men myth... I am in the middle of a biography of J R Oppenheimer... It is curious to me how seldom the moral question actually arose before the fact, and how little a part it played after Hiroshima....Oppenheimer did what he could to bring about the peaceful use of nuclear power, and to limit the arms race; but when he said to Truman that he "had blood on his hands" Truman flipped, since he was the one who set it off... In most expository writing on any subject it is the reader who must be aware of, and ask the moral questions...