During the period of Emperor Xuan of Han Dynasty, Qiang people invaded the border. Cities and lands, burning and plundering. Emperor Xuan of the Han Dynasty called together the officials to discuss countermeasures and asked who would like to lead the troops to exterminate the enemy. Zhao Chongguo, a 76 year old veteran, has dealt with Qiang people for decades on the border. He volunteered to take on the task. Emperor Xuan asked how many soldiers and horses he wanted to send. He said, "it's better to see them with my own eyes if i listen to them a hundred times. It's hard to figure out how to use troops far away from the battlefield. I'd like to go there and have a look in person. Then I'll make a plan of attack and defense, draw a map of the battle, and play it to your majesty. " Emperor Xuan of Han agreed. Zhao Chongguo led a team of people to set out. The troops crossed the Yellow River and met a small group of Qiang troops. When the soldiers were ready to take advantage of the victory, Zhao Chongguo stopped them and said, "our army has traveled a long way here, and we can't go far. If you are ambushed by enemy soldiers, you will suffer a great loss! " After listening, his subordinates admire the veteran's insight. Zhao Chongguo observed the terrain, learned the internal situation of the enemy from the captives, understood the enemy's troop deployment, and then formulated the strategy of garrison, border control, and disintegration of Qiang people, report all information to Emperor Xuan of Han Dynasty. Soon later, the court sent troops to settle the invasion of Qiang people and stabilize the northwest frontier.