Can someone explain what the purge trails are?

Napoleon’s execution assembly represents the Moscow Trials and the Great Purge, Stalin’s widespread campaign to suppress any and all dissent in the Soviet Union. Indeed, this was a far cry from the cooperation and good cheer with which the Animalism revolution began. In the Soviet Union, it began as a “cleansing” of the Communist Party and was expanded to one of the entire, vast Soviet population, among which tens of millions were killed or deported. In the Moscow Trials of 1936-1938, Stalin incriminated many party leaders, charging them with crimes ranging from conspiracy to attempted assassination. The accused gave their confessions, seemingly freely in front of a general assembly, just as Napoleon’s accused give theirs in front of all the other animals.