The battle of defending Nanjing should be said to be the most painful battle. You should be able to think of what happened after the failure.
The Battle of Taierzhuang, the biggest victory since War of Resistance against Japanese Aggression, can be said to be a large-scale battle at the turning point of the Anti-Japanese War.
The Hundred Regiments War started after the name of the Eighth Route Battle.
These are some of the most classic and representative battles.