Gustave de Bellecourt was Secretary of the French legation in China in 1857, under Jean-Baptiste Louis Gros. He participated to the operation against China in the Second Opium War.Correspondence relative to the Earl of Elgin's special missions to China Great Britain. Foreign Office p.99 In 1858, Gustave Duchesne de Bellecourt arrived in Japan as the secretary of the mission for the Franco-Japanese Treaty of Trade and Amity, led by Jean-Baptiste Louis Gros.
