The first production from Frontier Films, the film production collective that was the successor to NYKino and the Workers Film and Photo League, Heart of Spain focuses on the Spanish Civil War, a conflict that became a touchstone of its era and was the most forceful opposition to the rising threat of fascism in Europe. Heart of Spain was begun by Geza Karpathi and Herbert Kline, who ultimately turned their footage over to Paul Strand, Leo Hurwitz, and Ben Maddow to make the film. It is compelling both for its shrewd formal aesthetics and as a sympathetic human document of the war.