When Lou decided to hide completely, he did not actively blind himself, and thus, he sent spies outside. For safety, he did not gather them but let them disperse throughout the camp. These spies naturally detected the advancing enemy army in advance. Some with strong capabilities immediately ran back to report, while some unfortunate ones were captured by the enemy and inadvertently contributed points to the enemy.
However, those chosen to be spies naturally had a talent for this, and their abilities were not lacking. The spies who were killed were few; most of them were carefully lurking, diligently gathering information within the competition field.
Ji You led the army but only stayed a short while in Lou's 5th camp before quickly retreating. This significant move was, of course, known by the spies lurking around. A few particularly daring ones, emboldened by their skills, even quietly followed Ji You's army.
