Complex sentence: William Gilmore Simms (April 17,1806--June 11,1870) was a poet, novelist and historian from the American South whose novels achieved great prominence during the 19th century, with Edgar Allan Poe pronouncing him the best novelist America had ever produced.
Split into simpler sentences: William Gilmore Simms (April 17,1806--June 11,1870) was a poet, novelist and historian from the American South. His writings achieved great prominence during the 19th century, with Edgar Allan Poe pronouncing him the best novelist America had ever produced.