Question: when did the us split into north and south
[{'answer': 'the Civil War', 'provenance': [{'wikipedia_id': '863', 'title': 'American Civil War', 'start_paragraph_id': 1, 'start_character': 229, 'end_paragraph_id': 1, 'end_character': 242, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]