The Wall That Was a GateHow to make a fortress useless with poor pay.

From the show

When Rewards Backfire

China's Great Wall was an unparalleled feat of engineering, meant to keep invaders out. Yet, it was ultimately compromised from within. This story reveals how a simple economic oversight—underpaying the guards—turned the world's greatest defense into an open door for its enemies. It's a stark reminder that a system's strength lies not just in its physical barriers, but in the incentives that govern its people.