Complex sentence: Most of the letters are adressed to Ortwin Gratius and contain mock accusations against him, such as allegation that he had been intimate with Johannes Pfefferkorn's wife (Letter XII) and that Gratius had defecated his pants in public (letter XL).
Split into simpler sentences: Most of the letters are adressed to Ortwin Gratius and are base slanders against him. They contain allegations such as he had been intimate with Johannes Pfefferkorn's wife (Letter XII) and that Gratius had defecated his pants in public (letter XL).