system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] How did the Dai Li hide the war when Uncle Iroh was attacking Ba Sing Se and almost conquered the city?

How did they hide a massive battle right outside from the Earth King and the citizens? Wouldn't they hear the explosions, see the massive mobilization of troops, and have lots of casualties?
gpt
Have you seen Baa Sing Se on a map? It's estimated at ~100 miles in diameter. There are many miles of farmland, mountains, and lakes between the Outer Wall and the central districts. 

The common citizens all know about the war, it's just the king who it's kept secret from.