Question: where was the initial german offensive on world war i western front stopped in september 1914
[{'answer': 'First Battle of the Marne', 'provenance': [{'wikipedia_id': '51499', 'title': 'Western Front (World War I)', 'start_paragraph_id': 10, 'start_character': 11, 'end_paragraph_id': 10, 'end_character': 36, 'bleu_score': 1.0, 'section': 'Section::::1914.:War plans – Battle of the Frontiers.\n'}]}, {'provenance': [{'wikipedia_id': '51499', 'title': 'Western Front (World War I)', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 832, 'bleu_score': 0.9246581398968471, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15412526624201306543}, 'section': 'Section::::1914.:First Battle of the Marne.\n'}]}]