why did the people of molching hold a bonfire? what shocking realization met liesel when she listened to the speaker at the bonfire?

The bonfire is part of the celebrations for Hitler's birthday. Propaganda, banned and censored books, and written material from the era between World War I to the rise of the Nazis are collected. The Speaker starts talking about Communism and Liesel revisits her dark past. She sees a girl in pigtails staring at the fire which reminds Liesel of herself.