In the early morning of May 6, a Tubo cavalry of more than 200 people attacked a village on the border of Chidu County, Qinghai Prefecture, at the northern foot of the Qilian Mountains, and captured hundreds of Tang Dynasty civilians.

After Tuyuhun was incorporated into the Tang Dynasty, the army of the whole country was unified into the Qinghai Military Region, the main force was the Second Cavalry Division of the Tang Army of the former Longyou Military Region, the 22nd, 23rd, 24th, and 25th Provisional Cavalry Divisions of the Tuyuhun Plain Army, and the 31st and 32nd Infantry Divisions, with a total strength of 82,000 people.

During the war, the border areas generally adopted the management model of military and political integration, and Chidu County was subordinate to the jurisdiction of the 23rd Provisional Cavalry Division.

After being attacked, the people who ran out to report the news found the troops of the 23rd Cavalry Division and asked for rescue. The 23rd Cavalry Division sent troops of a cavalry battalion to the rescue in an emergency.

The officers and men of the cavalry battalion rushed to the scene of the accident and were stunned by the tragic situation in the village.

Outside the village, mutilated corpses and dripping blood, a fire broke out in the village, and thick smoke billowed from the village.

The officers and men of the cavalry battalion stared at blood-red eyes, galloped on horseback, and desperately pursued.

When the cavalry battalion arrived at the border, they found that the Tibetans had entered the Tibetan side, but they could be seen from a distance.

As soon as the battle began, there was no concept of the border line for a long time, and the officers and men of the cavalry battalion chased after them on horseback.

There were about 200 Tibetans, all of whom were cavalry, and they were overtaken by the officers and soldiers of the cavalry battalion because they were escorting the people marching on foot.

Seeing that the Tubo people were approaching, the cavalry battalion commander shouted: "The second company is to the left, the third company is to the right, the two flanks are outflanked, don't let the Tubo people go." He himself led the rest of the cavalry and rushed straight over.

When the Tubo people saw the Tang cavalry appear, they did not panic, they left a few cavalry to guard the Tang people, and the rest of the cavalry gathered to meet the cavalry of the Tang army.

A cavalry battalion of the Tang Army's provisional division had a strength of 540 people, excluding the people left behind, and this time there were 480 people, twice as many as the Tibetan cavalry, and they quickly surrounded the Tibetan cavalry in the middle.

The provisional division of the Tang Army was adapted from the Tuyuhun army, and the weapons and equipment had not had time to be changed, but they were only changed into the military uniforms of the Tang Army, and their combat effectiveness was basically close to that of the Tubo people.

Although the strength of the Tubo people was small, they did not choose to flee, but gathered together and formed a circle to engage the Tang army. Although the Tang army was numerous, it was impossible to defeat it for a while.

After fighting, the cavalry battalion commander felt that something was wrong, and he believed that the Tubo people were small in number and should retreat to the depth of their own territory, but they chose to take the risk of entanglement with the Tang army, which was inconsistent with the art of war.

At this moment, he saw a large group of Tibetan cavalry appear on both sides. There is also a unit outflanking the rear road of the Tang Army.

"I've been tricked." The commander of the cavalry battalion was shocked and hurriedly ordered to retreat.

This is really a ploy of the Tibetan people. When the Tibetans sent a small force to cross the border to sneak attack, they hid a large group of men and horses on their own side of the border.

If the Tang army did not pursue, they could successfully complete the task of harassment. If they encountered the pursuit of the Tang army, they would hug the grass and beat the rabbits, and by the way, ambush the pursuing troops of the Tang army.

The Tang army was entangled with the Tubo people at this time, and it was not so easy to retreat.

The commander of the cavalry battalion had no choice but to break his wrist and order to entangle the Tubo people after a series of breaks, and he led the rest of the troops to rush towards the territory of the Tang Dynasty.

Due to the shallow depth of the Tang army's entry into the territory of Tibet, at this time, the outflanking troops of the Tubo people had not yet been able to form an encirclement, and the Tang army fled with their lives, and finally fled into the territory of the Tang Dynasty before the Tubo people closed the siege.

The Tibetans did not chase after them, but gave them a ride with bows and arrows, and then went to encircle the troops after the Tang army was broken.

The Tubo people who besieged the troops after the Tang army broke off were 2,000 people. The cavalry company commander watched his men being annihilated by the Tibetans, but he had no choice but to go back and report in despair.

In this battle, the Tang army was defeated, not only did not rescue any of the captured people, but lost nearly 200 cavalry.

Recently, the commander of the Qinghai Military Region, Ashinahun (the uncle of the imperial concubine Ashinaqing), received many similar reports that the Tang army had suffered a lot of losses in the sneak attack with the Tubos.

He had long wanted to retaliate on a large scale, but he had already received orders to carry out only small-scale raids, with no more than 1,000 troops to be dispatched at a time. It was necessary to wait for the entire units of the Don Army, ready for a full-scale war, before launching a large-scale offensive.

At this time, the king of Qinghai County, Nuo Haobo, returned to the original Tuyuhun King City Fu Qi City, which is now the Qinghai Provincial Supervision and Governor's Office.

Nuo Haobo is the deputy commander of the Tibetan Expeditionary Force, and the main strength of the Qinghai Military Region is the Tuyuhun people, who have just joined the Tang Dynasty and are eager to show their loyalty to His Majesty the Emperor, and also want to make a name for themselves on the front of Qinghai Road.

Nuo Haobo and Ashina Hongdi had the same idea, so they decided to take the lead in launching an attack on Tibet.

The eastern section of Qilian Mountain, the mountain is steep, Tuyuhun enters a main valley of Tubo, there is an extremely narrow place, the narrowest place is only 20 meters, there are strange rocks on both sides here, there is a protruding rock, the shape is like an eagle's beak, commonly known as the eagle's beak rock.

The Tibetans built a pass in the Eagle's Beak Rock, and the pass was called the Eagle's Beak Pass.

The Tibetans had stationed 200 people for defense in peacetime, but now they were in a state of war, and the Tibetans added another 500 people to strengthen the defense.

The problem is that the soldiers can climb it with their bare hands, but the various baggage of logistics cannot climb over the mountains, so in order to ensure the movement of the army, the Eagle Beak Rock Pass has become a key point that both sides must control.

In the early morning of May 21, the 1st Regiment of the 31st Infantry Division of the Tang Army crossed the eastern section of Qilian Mountain and appeared behind the side of the Eagle's Beak Rock, where they were going to make a detour to attack the Eagle's Beak Pass.

When they arrived near the Eagle's Beak Pass, they found that the surrounding mountains were full of Tibetan figures. It seems that the Tibetans have stepped up their precautions.

Accompanying the operation of the 1st Regiment were 50 soldiers of a reinforced detachment of the Flying Tigers, who were selected from the Flying Tigers to climb masters.

Seeing that the Tubo people had already taken precautions, in order not to expose the battle attempt, Huang Haiming, the commander of the Flying Tiger Army, discussed with Ge Luohan, the commander of the first regiment, that the troops would hide on the spot for a day and wait until night to launch a surprise attack.

The commander of the 1st regiment, Glohan, agreed with this opinion and sent someone to report to the command.

The Tang Army's current position on the Qilian Mountain is 4,200 meters above sea level, and the snow on the top of the mountain has not yet subsided, and the officers and soldiers are huddled behind the ridge, enduring the biting cold wind, to survive this long day.

However, that's not the saddest issue.