The Bus de la Lum was the scene of a tragic event, the historicity of which is disputed and at the center of a bitter controversy.
During the Second World War, the cesspool was used by partisans (the resistance was particularly active in the Cansiglio area) to dump the bodies of several soldiers of the Italian Social Republic and German soldiers, as well as civilians. Burial in natural caves has led some sources to compare this event to the Venezia Giulia (the Foibe) massacres.
According to the association Silentes Loquimur, created specifically to commemorate the victims of the Bus de La Lum, a 1949 report by the Carabinieri of Vittorio Veneto counted over 300 victims, while the speleologists of the Italian Cave Rescue Center were working on theirs Investigations in the 1960s assumed up to 500 victims (200 German soldiers, 100 RSI soldiers, 200 civilians). The same association reports that in the early 1950s the remains of 26 people were recovered, while a search carried out in 1992 turned up another 68 people who were later buried in the Caneva cemetery. No further surgeries have been performed since then due to the high economic cost.
According to Umberto Lorenzoni, president of the Treviso ANPI, "no more than a dozen skeletons were recovered" from the Bus de la Lum; and when, in the early 1990s, the president of the ANPI of Pordenone, Bruno Giust, asked for further investigations to be opened, "we were told by the president of the Victims' Association that it was not appropriate to proceed. Obviously because, in our opinion, there was nothing else to be found gave". He concluded that the Bus de La Lum was used as an improvised burial ground in the final months of the war, at a time "when nothing else could be made available".