This form is based on the natural rhythms of phrases and normal pauses, rather than the constraints of metrical feet. Commonly called Vers libre in French, the poetry often involved the counterpoint of stressed and unstressed syllables in unpredictable but clever ways.
American poet Walt Whitman first made extended, successful use of the free verse, and he in turn influenced Baudelaire, who developed the technique in French poetry. In the late 19th and early 20th centuries, we find several poets using some variant of free verse—including Ezra Pound, T. S. Eliot, D. H. Lawrence, William Carlos Williams, and E.E. Cummings.