Question: after a six week siege what city surrendered to grant's army
[{'answer': 'Vicksburg', 'provenance': [{'wikipedia_id': '229668', 'title': 'Siege of Vicksburg', 'start_paragraph_id': 0, 'start_character': 9, 'end_paragraph_id': 0, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '229668', 'title': 'Siege of Vicksburg', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 458, 'bleu_score': 0.8164424391466121, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17997215436401677458}, 'section': 'Section::::Abstract.'}]}]