Question: who won the civil war battle of antietam
[{'answer': 'Union', 'provenance': [{'wikipedia_id': '84849', 'title': 'Battle of Antietam', 'start_paragraph_id': 1, 'start_character': 253, 'end_paragraph_id': 1, 'end_character': 258, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '84849', 'title': 'Battle of Antietam', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 681, 'bleu_score': 0.9451682112936691, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2201083737684837047}, 'section': 'Section::::Abstract.'}]}]