Louis Franquet was baptized on June 11, 1697, in Condé-sur-l’Escaut, dept. of Nord, France.

Franquet was a French army officer and military engineer. He was commissioned into the army at the age of 12 and served in the infantry regiments of Franclieu, Miroménil, and Piémont from 1709 to 1720. In 1720, he joined the engineer corps, where he distinguished himself in Europe for the next 30 years. After participating in the Italian campaigns during the War of the Polish Succession from 1733 to 1736, he was appointed chief engineer at Condé in 1738. In 1741, he was awarded the cross of Saint-Louis. He was promoted to lieutenant colonel in 1747 but was wounded that same year at the siege of Bergen op Zoom.

In 1750, while serving as chief engineer at Saint-Omer, Franquet was asked to travel to Île Royale (Cape Breton Island) to assess the colony's defenses. His mission was to strengthen the fortifications at Louisbourg, including coastal defenses and batteries, in preparation for a potential British attack in the mid-18th century. Although his work focused on coastal defenses, his expertise in military engineering and fortifications was also crucial for defending French territories along the Ottawa River—a vital transportation route and boundary between Ontario and Quebec.

Upon arriving at Louisbourg in August 1750, Franquet examined buildings and fortifications, prepared maps and plans, and conducted experiments to identify the causes of structural deterioration. In 1751, he toured the rest of Île Royale, as well as Île Saint-Jean (Prince Edward Island), Baie-Verte, and Fort Beauséjour in New Brunswick. During this tour, he completed many plans and detailed reports on the fortifications at Louisbourg, making recommendations for necessary improvements. In the same year, he was promoted to colonel.

Between 1752 and 1753, Franquet travelled throughout Canada, examining fortifications and buildings in Quebec, Trois-Rivières, Montreal, and other towns and forts. He observed nearly every aspect of Canadian life. Franquet is remembered for his numerous maps and plans, his contributions to the construction of the original Louisbourg, and his reports from 1751, 1752, and 1753, which reflect his interest in the customs and lifestyles of the Indigenous peoples, Acadians, and Canadians.

He died on April 12, 1768, at Condé, France.