In 1931, "Kenkyūsha" undertook a major revision in the dictionary by expanding upon former entries and adding newer ones. The British diplomat George Sansom, who later became a renowned historian of Japan, was a major contributor and editor of this edition. Aside from the ever-evolving nature of the Japanese and English languages, competition from two other major dictionaries released in the 1920s – "Takehara's Japanese–English Dictionary" and "Saitō's Japanese–English Dictionary", both of which were larger than the first edition of "Kenkyūsha's" – was probably a major driving force behind these revisions (although new editions of these dictionaries were never released, allowing "Kenkyūsha's" to assert and maintain its dominance among Japanese–English dictionaries). From this second edition onward, the dictionary became known as "Kenkyusha’s New Japanese–English Dictionary". During World War II, reputable institutions in the United States and Great Britain, including Harvard University's Department of Far Eastern Languages, produced pirated versions of this dictionary for the war effort.