1871: Esperantist Persecution Jan 29, 2020

The turn of the last century saw the rise of many utopian visions, including socialism and fascism, and the targeting of Esperanto speakers—to the point of imprisonment and execution—was found in both. That's been mentioned here before, but it is worth noting that the respective reasons were very similar, despite many supposed difference in the two systems. Both fascist governments, in Germany and Japan, and Soviet governments feared supranational left-wing revolutionary ideas that underpinned the pacifistic Esperantist movement. This is still true in the case of the Soviets, who were themselves nominally revolutionaries hoping for a new, supranational left-wing society, because these Esperantists would be able to communicate outside of the Soviet union. Ironically, the only thing that stopped the Soviet persecution of Esperantists was an invasion of the Nazis, who also systematically attacked Esperantists, but less so numerically speaking.

Recommended reading: Concise Encyclopedia of the Original Literature of Esperanto, 1887-2007