Lieutenant Commander Douglas R. Cassel was a United States Naval Officer and veteran of the American Civil War known for his service to Meiji Japan's armed forces.

A month later he participated in the United States punitive expedition against Korea, where he commanded the Alaska's two howitzer batteries, seven guns total, which were dragged across a mud flat to support the main column during the Battle of Ganghwa.

[1] Four months later, Cassel transferred to the USS Ashuelot, temporarily acting as her commander from December 1873 to March 1874, before being contacted by the Japanese government to assist in modernizing its navy.

Cassel successfully requested a 1-year leave of absence to serve in the employ of the Japanese government, which was endorsed by United States Minister to Japan John Bingham, where he was to earn $7,000 and the rank of captain.

[3] During the expedition Cassel voiced many frustrations with Japanese disobedience and lack of restraint, particularly among the shizoku who understood warfare primarily in the samurai ethos of taking risks to attain honor.

In letters to Charles Le Gendre, Cassel referred to General Tani Tateki as a "little imbecile", and also argued with Admiral Noriyoshi Akamatsu for his plans to attack friendly tribes as punishment for an incident where shots were fired at survey boats of the Nisshin, as well as his alleged lack of control over his men.