The idea of destroying knowledge to defeat one's enemies is an amazing thought process. Conquer them and access the knowledge. Don't destroy it.
Julius was quite educated and claimed it burned by accident. To make up for it he endowed about 20 major libraries in Italy.
China went through a revolution in ancient times in which nearly all books were destroyed. Someone built hollow walls in a house and save a bunch. Otherwise we'd know even less about the history of China.