Question: when was the last declared war in the us
[{'answer': 'World War II', 'provenance': [{'wikipedia_id': '455614', 'title': 'Declaration of war by the United States', 'start_paragraph_id': 12, 'start_character': 3, 'end_paragraph_id': 12, 'end_character': 15, 'bleu_score': 1.0, 'section': 'Section::::Declarations of war.:Formal.\n'}]}]