Castles don't stop armies from advancing, right ?

[Meglobob]

I understand your point but I do not really agree with it.

In real life castles where built at strategic or important locations. A castle was meant to slow a army, or inflict massive casualtys on armies that came too close (Baltic sea fortresses for example) or to force a army to take a longer route and finally to provide a secure base to raid a army from behind.

Castles being immoble were never designed to completely stop a army.

One final example, the wall of china was not designed to keep barbarians out but make it difficult for them to escape with the loot.