Complex sentence: Paul Éluard was the "nom de plume" of Eugène Grindel (December 14,1895--November 18,1952), a French poet who was active in the Dada and Surrealist movements.
Split into simpler sentences: Paul Éluard was the "nom de plume" of Eugène Grindel (December 14,1895--November 18,1952), a French poet. He was active in the Dada and Surrealist movements.