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In page Lydia Koidula:

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Koidula's most important work, Emajõe ööbik, (The Nightingale of the Emajõgi River), was published in 1867.[1] Three years earlier, in 1864, Adam Peterson, a farmer, and Johann Köler, a fashionable Estonian portraitist living in Saint Petersburg, had petitioned the emperor for better treatment from the German landowners who ruled the Baltic provinces, equality, and for the language of secondary and higher education to be Estonian instead of German. Immediately afterwards, they were taken to the police, where they were interrogated about a petition that 'included false information and was directed against the state'. Adam Peterson was sentenced to imprisonment for a year.[citation needed]