One day, Emperor Taizong gave a banquet to his ministers in the palace. In order to please Emperor Taizong, he suggested that Emperor Taizong send troops to attack Liao. Emperor Taizong originally had this intention, so in order to build momentum, he asked him for advice in front of his ministers. Emperor Taizong asked him, "What are the favorable conditions for my Great Song Dynasty to attack Liao at this time?" The minister saw that Emperor Taizong really liked this topic, so his eyebrows fluttered, and he said eloquently, "Emperor Liao is young and newly established, and the Empress Dowager Xiao is regent, and the monarch and ministers will inevitably lose harmony, and now my Great Song Dynasty soldiers are strong and strong, and it is the best time for the Northern Expedition." "Song Taizong originally had the intention of the Northern Expedition, and when he said this, he was suddenly overjoyed, and he didn't listen to any other opinions. Emperor Taizong thought that the time was quite ripe for the Northern Expedition, so he summoned the civil and military ministers to discuss decisions and assign tasks. Emperor Taizong was full of confidence and was determined to capture the land of clouds in one fell swoop, dealing a heavy blow to the Liao soldiers, and avenging the revenge of the year and the shame of the year.

The Song army was divided into three routes and attacked Liao on a large scale. The Eastern Route Army was the main force of the Song army, with Cao Bin as the commander, and went out of Xiongzhou to attack Nanjing, Liao. The Middle Route Army, with Tian Chongjin as the commander, went out of Feihukou and captured the northern part of Hebei. The Western Route Army, with Pan Mei as the commander, Yang Ye as the deputy commander, and Wang Yu as the protector, went out of Yanmen Pass and captured the northern part of Shanxi.

According to Emperor Taizong's deployment, the Eastern Route Army advanced slowly, first capturing Zhuozhou to attract the main force of the Liao army. After the Middle Route Army and the Western Route Army advanced to the north of Liao's Nanjing, they would join forces with the Eastern Route Army to attack Nanjing.

At the beginning of the war, due to the preemptive strike of the Song army, the attack was quite smooth, and the Song army conquered many prefectures and counties in Liao. But in the face of the all-out attack of the Song army, the Liao State began to resist with all its might. The Liao army, especially the cavalry, was extremely combative. Seeing that the enemy was being attacked on all sides and the situation was critical, Yelu Longxu and Empress Dowager Xiao of Liao Shengzong personally went to Nanjing to supervise the battle. In this way, the situation of the war quickly turned, and the two sides faced off for some time. Later, the Song Army's East Route Army and the main force of the Liao Army fought a decisive battle at Qigou Pass, forty miles southwest of Zhuozhou. The Song army was defeated by the Liao army, with tens of thousands of casualties. When Emperor Taizong heard the news, he was quite frightened and urgently ordered the Song army to retreat on all fronts.

When the Western Route Army retreated, it was pursued by the Liao army. At this time, the Liao army was in full swing, and Yang Ye, the deputy marshal, thought that it was not possible to fight to the death with the Liao army, and should temporarily avoid its front. However, the coach Pan Mei and the protector Wang Yu advocated a head-to-head confrontation with the Liao soldiers. Not only that, Pan Mei and Wang Yu also reprimanded Yang Ye for being cowardly and fearful of the enemy, and even falsely accused Yang Ye of harboring different aspirations. Yang Ye was not only coerced, but also falsely accused, and had no choice but to lead the army north.

Yang Ye knew that this trip would be a defeat or a win, and he still wanted to minimize the loss as much as possible. In order to get lucky, before sending troops, Yang Ye made a special agreement with Pan Mei and Wang Yu. It was agreed that Pan Mei and Wang Yu would arrange infantry hard crossbows on both sides of the Chenjia Valley Pass, and when Yang Ye transferred to this place, they would use the infantry on both sides to flank the Liao army and rescue them.

Yang Ye's lone army went deep into the Liao region and met the Liao soldiers on the way. The Liao army attacked the Song army from all sides, and the Song army suffered heavy casualties. After several battles to the death, Yang Ye led the army to break out of the encirclement and retreated to Langya Village, and soon was chased by the Liao army.

Yang Ye and others had no choice but to fight to the death with the Liao army, and the Song army suffered casualties all day. Yang Ye only led more than 100 soldiers to retreat to the Chenjia Valley Pass as agreed in advance at dusk. When he arrived at the mouth of Chenjia Valley, the Liao soldiers were so big, but there were no reinforcements, Yang Ye was in great pain in his chest, and sighed!

It turned out that after Yang Ye led his troops to set off, Pan Mei and Wang Yu agreed to Chen Bing at Chenjiagukou. It was nearly noon, and there was no news of Yang Ye's battle situation. Pan Mei and Wang Yu sent people to climb the high platform and look into the distance, but when they couldn't see it, they thought that the Liao army had been defeated by Yang Ye.

Wang Yu was bent on competing for merit and receiving rewards, completely ignoring the prior agreement. Wang Yu personally led the troops and horses of his headquarters, broke away from the brigade without authorization, and went to snatch the merit of breaking Liao. Pan Mei, as the head coach, is not restrained by this. Soon after, Pan Mei also withdrew with the main force. Wang Yu led the army for more than 20 miles before learning the news of Yang Ye's defeat. At this time, he was terrified and fled in a hurry.

Poor Yang Ye, who was known as "Yang Invincible", was alone, so he led the rest of his army to fight to the death with the Liao army. More than 100 soldiers were killed and wounded, and Yang Ye was severely injured in dozens of places and was captured with all his strength. After Yang Ye was seriously injured and captured, he was righteous and awe-inspiring, preferring to die rather than give in, and died on a hunger strike for three days. The Liao army took advantage of the victory to attack the Song realm, and the Great Song suffered heavy losses. Hearing the news that Yang Ye was captured and martyred, the Great Song Dynasty was shocked.

Emperor Taizong miscalculated the situation, and the Song army won first and then lost, and this result made him completely lose confidence. From then on, Emperor Taizong couldn't protect himself, and he didn't think about it anymore, seizing the land of clouds. From then on, he took a defensive position in Liao, and turned his main forces to the prevention and suppression of the people at home.

Although the Liao State had strong cavalry, it was helpless for a while in the face of the Song State, which had a vast territory and a strong economy. In this way, a long-term confrontation situation has been formed between the two countries. Liao Shengzong, Chengtianhou, Corporal Lixian, reformed politics, strengthened the army, and the Liao State was also in its heyday.