The King's Messengers

A king maintained a chain of signal towers across his realm. Each tower watched for fire from the tower before it, then lit its own.

A message could cross the kingdom in an hour.

One night, a storm knocked down the seventh tower. No fire was lit. The eighth tower saw nothing. Nor the ninth. Nor any after.

The enemy attacked the eastern border. The western armies never moved.

It was not the storm that defeated the king. It was the design that let a single fallen tower silence all the ones beyond it.