In 1943 Allied bombs destroyed the archives of Leoncavallo's publisher, Sonzogno, and of the Teatro Dal Verme, where Pagliacci was first performed. As a result, many sources pertaining to the opera's compositional history were lost, and scholarship has relied almost exclusively on Leoncavallo's unpublished autobiographical manuscript, “Appunti.” Contextual sources such as notifications in the press, eyewitness accounts, and a large body of mostly unpublished correspondence now suggest that Leoncavallo cloaked the opera's genesis to protect its legacy.
Leoncavallo was twice charged with having imitated an existing play. In his protracted defense, he took every opportunity to distinguish his libretto from the literary tradition to which it belongs and tie it instead to the verismo movement (with which critics had associated it since the premiere). He began to claim, for instance, that the libretto was based on a crime of passion he had witnessed in Montalto and invented a version of that crime that matched the libretto. Furthermore, in preparation of the first performance in Paris, he actively contributed to a staging faithfully depicting Montalto in an attempt to highlight the originality of the story. And as he was tightening the opera's connection to verismo, he was concealing aspects that would have reflected poorly on the opera's reception, including Sonzogno's initial concerns regarding the music and the presence of substantial musical self-borrowings.