What is the fine-grained topic of the following text: A young boy, who leaves his family at a critical junction in history becoming a true voyageur and later the first Allard citizen of Détroit, his lifetime encompasses a vital period in the development of Cadillac’s city in the wilderness as well as that of the American nation. Only return the topic.
The life and contributions of the first Allard citizen of Détroit during the development of Cadillac's city and the American nation.