Question: when did the battle of bull run start
[{'answer': 'July 21 , 1861', 'provenance': [{'wikipedia_id': '228867', 'title': 'First Battle of Bull Run', 'start_paragraph_id': 93, 'start_character': 51, 'end_paragraph_id': 93, 'end_character': 65, 'bleu_score': 1.0, 'section': 'Section::::Aftermath.:Detailed casualties.:Confederate.\n'}]}, {'answer': '5 : 15 a.m.'}, {'provenance': [{'wikipedia_id': '228867', 'title': 'First Battle of Bull Run', 'start_paragraph_id': 1, 'start_character': 17, 'end_paragraph_id': 1, 'end_character': 679, 'bleu_score': 0.9071670544464081, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13561664518980509672}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '228867', 'title': 'First Battle of Bull Run', 'start_paragraph_id': 65, 'start_character': 0, 'end_paragraph_id': 65, 'end_character': 797, 'bleu_score': 0.9641208621620131, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13561664518980509672}, 'section': 'Section::::Battle.:Morning phase.:Matthews Hill.\n'}]}, {'provenance': [{'wikipedia_id': '228867', 'title': 'First Battle of Bull Run', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13561664518980509672}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '228867', 'title': 'First Battle of Bull Run', 'section': 'Section::::Aftermath.:Detailed casualties.:Confederate.\n', 'start_paragraph_id': 93, 'end_paragraph_id': 93, 'meta': {'evidence_span': ['Confederate casualties at the battle of Bull Run, July 21, 1861', '"Confederate casualties at the battle of Bull Run, July 21, 1861."', 'Confederate casualties at the battle of Bull Run, July 21, 1861."']}}]}]