In 1869, DeLong travelled to Japan with his wife Elida and two small children. On November 11, 1869, DeLong presented his credentials to
Emperor Meiji of
Japan as
Resident Minister of the United States Consulate in Japan. In the name of the United States, he recognized the legitimacy of Japan's sovereignty over the
Ryukyu Islands. His wife Elida DeLong chaperoned five Japanese girls who were sent to attend American schools as part of the mission. Also in 1871, he negotiated a trade agreement between Hawaii and Japan. His position was elevated to that of
Envoy Extraordinary and Minister Plenipotentiary on June 9, 1872. He continued to serve in that capacity to October 7, 1873, although his career was marked by considerable friction with his superiors in Washington, who often accused him of overstepping his authority. ==Later life==