Treatise on Military Preparedness

...[the Wei army's] spirit is sharp. If we allow them to enter the flat lands, they will be unstoppable; we should block the mountain passes to resist them.

Murong Sui original: 睦邃; a general of Later Yan said: "The Wei have many cavalry, but their horses can only carry enough fodder to match their own grain rations—lasting no more than ten days. We should order the prefectures and counties to gather the people into their homes, forming fortified strongholds, and 'clear the fields' Clear the fields (qīng yě): A scorched-earth tactic where all crops and resources are removed or destroyed so the invading army cannot forage to wait them out. In no more than sixty days, their food will be exhausted, and they will retreat of their own accord."

Feng Yi said: "The Wei soldiers number in the hundreds of thousands. Even if the people build fortifications, they cannot hold them on their own. This would merely be gathering our people and grain together to provide for the enemy. Furthermore, such a move would shake the people's confidence and show our weakness. It is better to block the passes and engage them in battle."

Murong Lin, the Prince of Zhao, said: "The Wei vanguard is unstoppable. We should focus entirely on the defense of Zhongshan The capital of Later Yan, wait for them to grow weary, and then take advantage of their exhaustion."

Bao also did not permit it original: 覽亦不允; 'Lan' was the personal name of the Emperor Murong Bao. This note indicates he rejected the more proactive strategies

Thereupon, they repaired the city walls and stockpiled grain to prepare for a long-term siege, entrusting all military affairs to Murong Lin.

Tuoba Yi, the Duke of Dongping of Wei, attacked Ye A major strategic city in the North China Plain. Murong De, the Prince of Fanyang of Yan, sent Murong Qing, the Prince of Nan’an, and others at night...