Question: according to revisionist historians what was the primary cause of the civil war
[{'answer': "Defense of states ' rights", 'provenance': [{'wikipedia_id': '1405473', 'title': 'Lost Cause of the Confederacy', 'start_paragraph_id': 7, 'start_character': 75, 'end_paragraph_id': 7, 'end_character': 96, 'bleu_score': 0.668740304976422, 'section': 'Section::::History.:Antebellum foundation.\n'}]}]