Using wildcats and dogs as "eyes" can never compare to using birds.
Birds disregard terrain, flying straight from one place to another.
But wildcats and dogs have it tough; getting into the city is hard, and leaving it is harder...
Li Yuan simply stopped thinking about the cats and dogs in the city.
He tried hard to direct the wild cats and dogs outside towards the source of the sound.
However, the mountains that birds can fly over with a flap of their wings require wildcats to climb up and down.
The distance that birds can cover in a minute takes wildcats a full hour.
This made Li Yuan feel that Grand General Lü's "no-fly plan" was indeed halfway successful.
And soon, he realized it wasn't halfway successful but completely successful.
Because his eavesdropping also failed.
