Red Flag Incident
In the mixed political climate of the late Meiji, early Taishō periods, celebrated political activist and anarchist Koken Yamaguchi was discharged from a term in prison. His release was met with by crowd waving red flags carrying Anarchist Communist slogans such as Museifu Kyōsan (無政府共産 "anarcho-communism") and Kakumei (革命 "revolution") and a chorus of communist songs. The police attacked and suppressed the small demonstration, and ten prominent activists, including Ōsugi Sakae, Hitoshi Yamakawa, Kanno Sugako, and Kanson Arahata were arrested.
In later trials, most of the arrested were found guilty and received sentences of one year or more, with Ōsugi receiving the longest prison term. Although this is a relatively minor event in the complicated history of Meiji politics, it gained notability later when the incarceration of certain members of this scuffle (Sakae, Yamakawa and Arahata) protected them from being involved in a much more prominent protest, the High Treason Incident, which resulted in a number of activists being sentenced to death.
This incident marked the beginning of the fight of the imperial government against the socialist movement in Japan.