After his newspaper business failed, Whitman started on his best known work, "Leaves of Grass." It contains 12 untitled poems with a preface.

The Civil War was a catalyst for other writings of Whitman's. He published his diary notes and sketches in "Memoranda During the War." He saw the effects of war firsthand through his enlisted brother.

Much of Whitman's writing is on the cycle of life and death. He also used the Italian opera as an influence for his poetry. Whitman will be remembered as one of the first poets to use free verse.

-- Benet's Reader's Encyclopedia of American Literature