Were Japanese naval personnel seconded to the Harwich Force during World War I?
Short answerNo formal secondment is confirmed here. The tentative recollection is that the Japanese naval attaché visited regularly because of his relationships with Tyrwhitt and Keyes.
NotesThere is no confirmed secondment of Japanese naval personnel to the Harwich Force during World War I. A tentative recollection places the Japanese naval attaché at Harwich on regular visits because of his friendships with Reginald Tyrwhitt and Roger Keyes. The contact is relevant to Anglo-Japanese professional exchange. It does not show that one navy simply copied the other's doctrine.