Question: who won the battle of fredericksburg and chancellorsville
[{'answer': 'General Robert E. Lee', 'provenance': [{'wikipedia_id': '48780', 'title': 'Battle of Chancellorsville', 'start_paragraph_id': 1, 'start_character': 469, 'end_paragraph_id': 1, 'end_character': 490, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]