Polish–Lithuanian–Ruthenian Commonwealth (Polish: Rzeczpospolita Trojga Narodów, Commonwealth of Three Nations) was a proposed (but never actually created) European state in the 17th century that would replace contemporal Polish–Lithuanian Commonwealth. The creation of a Duchy of Ruthenia was considered at various times, particularly during the 1648 Cossack insurrection against Polish rule in Ukraine. Such a Ruthenian duchy, as proposed in the 1658 Treaty of Hadiach, would have been a full-fledged member of the Polish–Lithuanian Commonwealth, which would thereby have become a tripartite Polish–Lithuanian–Ruthenian Commonwealth. In May 1659, the Polish Diet (Sejm) ratified the treaty with an emended text.[1] The idea of a Ruthenian Duchy within the Commonwealth was completely abandoned.[2]
The Canadian historian Paul Robert Magosci believes that it happened due to divisions among the Cossacks and Muscovite invasion[3] which, however, both occurred much earlier than the Treaty of Hadiach was signed. The Russian historian Tairova-Yakovleva considers the resistance of the Polish society and the papal pressure as the reasons for the incomplete ratification.
