(The Ballad of Łupaszko), written while Szpotański was in Mokotów Prison, to the writer. In the aftermath of the 1968 events, Polish communist media, and communist leader, Władysław Gomułka, on 19 March 1968, alleged that in 1948 Jasienica was freed because he collaborated with the communist regime; this allegation caused much controversy and damaged Jasienica's reputation. He was subject to much invigilation (oversight) by the security services. In December 1969, five years after his first wife's death, he remarried. This marriage proved to be highly controversial as it was discovered after his death that his second wife, Zofia Darowska O’Bretenny, had been a secret police informant before their marriage, and continued to write reports about him throughout their marriage. From 1968 until his death, his books were prohibited from being distributed or printed. Jasienica died from cancer on 19 August 1970 in Warsaw. Some publicists later speculated to what extent his death was caused by "hounding from the party establishment". He is buried in Warsaw's Powązki Cemetery. His funeral was attended by many dissidents and became a political manifestation; Adam Michnik recalls seeing Antoni Słonimski, Stefan Kisielewski, Stanisław Stomma, Jerzy Andrzejewski, Jan Józef Lipski and Władysław Bartoszewski. Bohdan Cywiński read a letter from Antoni Gołubiew. Work Jasienica book publishing begun with a historical book, Zygmunt August na ziemiach dawnego Wielkiego Księstwa (Sigismund Augustus in the lands of the former Grand Duchy; 1935). He is best known for his highly acclaimed and popular historical books from the 1960s about Piast Poland, Jagiellon Poland and the Polish–Lithuanian Commonwealth: Polska Piastów (Piast Poland, 1960), Polska Jagiellonów (Jagiellon Poland, 1963) and the trilogy Rzeczpospolita Obojga Narodów (The Commonwealth of Both Nations, 1967–1972). This trilogy made him one of the most popular Polish history writers. Throughout his life he avoided writing about modern history, to minimize the influence that the official, communist Marxist historiography would have on his works. This was also one of the reasons for the popularity of his works, which were seen as a rare, legally obtainable alternative to the official version of history. His books, publication of which resumed once again after his death, were labeled as "best-selling", and became the most reprinted postwar history of Poland. His (Two ways, 1959) about the January Uprising of the 1860s represent the latest historical period he has tackled. His other popular historical books include , (Three chroniclers; 1964), a book about three medieval