The Spring and Autumn Period : An experienced person is a good guide 老馬識途

In 663 B.C., Duke Huan of Qi, at the request of Yan, sent an army to attack Shanrong, which had invaded Yan, with Guanzhong, the minister of the state, and Xiepeng, the doctor of the state, accompanying him. The Qi army set out in the spring, but by the time of the triumph, it was winter, and the grass and trees had changed. The army was wandering around in the valleys and finally lost its way and could not find its way back. Although several groups of spies were sent to explore the way, they still could not figure out where to get out of the valley. As time went by, the army had difficulties in feeding itself. The situation was so critical that if they could not find a way out, the army would be trapped here.