Complex sentence: After his 1927 divorce from Hadley Richardson, Hemingway married Pauline Pfeiffer; they divorced after he returned from the Spanish Civil War where he had been a journalist, and after which he wrote "For Whom the Bell Tolls".
Split into simpler sentences: After his 1927 divorce from Hadley Richardson, Hemingway married Pauline Pfeiffer. They divorced after he returned from the Spanish Civil War where he had been a journalist, and after which he wrote "For Whom the Bell Tolls".