Ems Ukaz
Ems Ukaz (sometimes Ems Ukase) was a secret ukaz of tsar Alexander II of Russia issued in 1876 banning the use of Ukrainian language in print, with the exception of reprinting of old documents. It was named after the city of Ems, Germany.
The Ems Ukaz was issued in response of the growing Ukrainian nationalism movement and unrest of Ukrainian cossacks. The ukaz also forbade the import of Ukrainian publications and staging plays in Ukrainian language.
The ukaz coincided with some other actions against Ukrainian national culture. The situation was exposed by professor Mykhailo Drahomanov (expelled from Kyiv University) in 1878 at the International Literary Congress in Paris.
Reference
Mykhailo Drahomanov (1878). La littérature oukrainienne, proscrite par le gouvernement russe: rapport présenté au Congrès littéraire de Paris (Ukrainian Literature Banned by the Russian Government: Report Presented at the Literary Congress in Paris), Geneva.