Question: who won the battle of antietam north or south
[{'answer': 'Union strategic victory', 'provenance': [{'wikipedia_id': '84849', 'title': 'Battle of Antietam', 'start_paragraph_id': 4, 'start_character': 425, 'end_paragraph_id': 4, 'end_character': 448, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]