Question: who commanded the british army at yorktown virginia
[{'answer': 'Lieutenant General Charles Cornwallis', 'provenance': [{'wikipedia_id': '157770', 'title': 'Siege of Yorktown', 'start_paragraph_id': 1, 'start_character': 398, 'end_paragraph_id': 1, 'end_character': 435, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '157770', 'title': 'Siege of Yorktown', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 897, 'bleu_score': 0.9865312178338931, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14806337498146202960}, 'section': 'Section::::Abstract.'}]}]