Cyrillization of Polish

The Cyrillization of Polish has been practised in many forms and began in the mid-19th century in the Russian Empire. Between 1772 and 1815, the Russian Empire seized about four fifths of Poland-Lithuania, where Polish was the leading official language. Polish remained the official language of the incorporated Polish-Lithuanian territories until the late 1830s. Later, it was gradually replaced with Russian through the mid-1860s. A middle stage for the transition was the use of the Russian-style Cyrillic for writing Polish.