The article presents a letter from Kazimierz Fryderyk Goebel (1893–1966), a soldier of the Polish Legions during World War I and an officer in the Polish Army during the Second Polish Republic, as well as the deputy director of the Postal and Telegraph Districts in Vilnius and Olsztyn. The letter, addressed to the Central Executive Committee of the Polish Socialist Party (PPS) in Warsaw, concerns an appeal against the decision to revoke his party membership. The analysis covers both the circumstances of the letter’s creation and its content, as well as the course of the appeal procedure itself. The letter serves as an individual example of the advancing process of Stalinization of political and social life in Poland following the meetings of the Central Committee of the Polish Workers’ Party (PPR) (August 31 – September 3, 1948) and the National Council of the PPS (September 18–22, 1948), and the decisions made there to effectively dismantle the socialist movement as part of the “purging the party ranks” prior to the so-called unification of the Polish labor movement.