Kammala jumla mai zuwa: Tattaunawar farko ta Sejm game da haɗin kai a watan Janairun 1569, kusa da garin Lublin na Poland, ba ta da amfani. Hakkin 'yan Poland na zama da mallakar ƙasa a cikin Grand Duchy ya yi tambaya daga jakadun Lithuania. Bayan tafiyar Mikołaj Radziwiłł daga Lublin a ranar 1 ga Maris, 1569, Sigismund ya ba da sanarwar haɗawa da lardunan Lithuania Podlachia, Volhynia, Podolia da Kiev a cikin Poland, tare da amincewa mai ƙarfi daga yankin Ruthenian (Ukrainian). Waɗannan yankuna na tarihi, waɗanda suka taɓa kasancewa na Kievan Rus', an yi jayayya tsakanin Lithuania da Rasha. Koyaya, manyan mutanen Ruthenian suna ɗokin yin amfani da damar siyasa ko tattalin arziƙin da Poland ke bayarwa kuma sun yarda da sharuɗɗan. A baya can, an soke Masarautar Ruthenia ko "Ukraine" a 1349, bayan Poland da Lithuania sun raba Ukraine ta zamani a bayan fadar
Galisiya da Volhynia Wars. Yanzu, a ƙarƙashin Union of Lublin, duk yankunan Ukrainian da Ruthenian waɗanda baƙi ne a cikin al'adu, al'adu, addini da yare ga mutanen Poland za a haɗa su da Poland Katolika. Za a biye da yammacin yamma da kuma Polonization, ciki har da ɓoye ɓoye na Ikilisiyar Orthodox na Gabas ta Gabas ta hanyar sarki na gaba Sigismund III. Ruthenia ya kasance a ƙarƙashin mulkin Poland har zuwa tashin hankali na Cossack da mamayar Poland da kuma rabuwa na Poland, lokacin da Daular Rasha ta haɗu da Ukraine.