The location of the second line of defense is not ideal for the first line of defense of the Huizhong Road tunnel, but fortunately, the engineering team has planted explosives in many places between the two lines of defense in advance, and the locations around the National Stadium, the Olympic Sports Center Natatorium, the Roller Skating Square and the Digital Museum have been arranged.

The blasting of the Huizhong Road tunnel brought unexpected results, when the situation in front was fed back to Shao Yifu, Shao Yifu decisively sent a third group of about 100 people to the Olympic Park Station of Metro Line 15, and extended the subway track of Line 15 to place high bao explosives, which is the third line of defense, and it is almost the last line of defense, and the subway is less than a kilometer past the Yenching Genomics Institute of the Chinese Academy of Sciences, where the Ministry of Tsinghua Union is located.

The last 100 fighters of Unit 61889 remained at the institute to make final defensive preparations. The explosives and munitions hoarded in the institute were distributed, and nothing was left behind. In the Olympic Village Science Park, some buildings have been temporarily converted into the last bastions, which have been transformed into fully enclosed structures, like living coffins. The warriors who entered the fortress were tantamount to giving up the chance to escape, and remained inside as outcasts who bought time to transfer work.

The helicopter brigade brought by Ge Congxian was still carrying out the transfer work in an orderly manner, and there was no longer a single soldier in the entire research institute to assist them. The gunshots and explosions of the distant battle were getting closer and closer, and the scientific researchers who had already boarded the plane were sweating for the soldiers on the front line, they all knew that their lives were won back by the soldiers with their own sacrifices, and some of them had already shed tears of sadness.

The helicopters took off one after another, Shao Yifu and Ge Congxian looked out the window at the helicopters that gradually disappeared into the sky, and their moods were different. Shao Yifu's mood was much lighter, most of the task was completed, and the rest of the work was to consider how to take as many fighters out as possible, the capacity of the helicopter brigade and the limitation of time factors caused the fighters of the institute to have no chance to board the plane, Shao Yifu did not want them to sacrifice here.

Ge Congxian was still thinking about persuading Shao Yifu to evacuate with the second batch of helicopters, but Shao Yifu's insistence made him more headed, because before he came, he had received a special advice from Rong Yun, and Rong Yun asked him to take Shao Yifu out, but if he couldn't do it, he could use special means.

"It seems that the chairman knows Lao Shao better," Ge Congxian sighed in his heart, chatted with Shao Yifu for a few words, and then turned around and left to make the next arrangement.

Shao Yifu looked back at Ge Congxian's back, feeling that Ge Congxian's expression was a little strange just now, and after thinking about it, he didn't find anything wrong.

As the helicopter flew over the Huizhong Road tunnel, the pilot of the plane looked down. The pit opened by Gao Bao's explosives has been filled with dense zombies, and the corpses on the south side of the tunnel continue to move north trying to pass through the pit, more zombies enter the pit, and the bodies of the zombies will gradually fill the pit.

Some of the zombies heard the sound of helicopters flying overhead, and looked up at the group, the flying of the helicopter did not attract the zombies for long, and their attention was always focused on the front.

The zombies on the north side of the tunnel have already begun to be blocked by the retreating defense forces, and the number of zombies that crossed the tunnel before the explosion of the high bao explosives in the tunnel is small, probably only a few thousand. The fighters began to stabilize their formation in the retreat and counterattacked. Time and life were passing, the number of casualties among the soldiers withdrawn from the first line of defense began to rise, the pressure on the front of the north side of the tunnel was much less than before, the soldiers relied on the terrain to fight and retreat, and the soldiers of the second line of defense also rushed forward to cover.

In the end, there were more than 400 soldiers who successfully retreated to the second line of defense, plus the 300 people on the original second line of defense, a total of less than 800 people, which was comparable to the defensive strength of the original first line of defense.

Xu Yongping continued to take command of the second line of defense and began to deploy defenses in the area near the defense line. To the east of the National Convention Center is the Yangshan River, which stretches south from Aohai and Wali Lake. Xu Yongping sent people to blast all the bridges across the Yangshan River, turning the Yangshan River into a natural barrier on the east side of the second line of defense. Several bridges on National Stadium North Road, Datun Road, Datun North Road and Kehui South Road collapsed in the blasting, and the vehicles on the bridges and the reinforced concrete of the bridge body fell into the river. After the destruction of the four bridges, the front of the second line of defense was compressed to 800 meters wide, and the width of the defense was about 1 meter per person, which was half the defensive pressure of the first line of defense.

The corpses that had previously been in the Huiyuan apartment area on the east side of the Bird's Nest were isolated east of the Yangshan River, and could not pose a threat to the defense line or the research institute for several hours. The remaining zombies in the zombie herd were about 60,000, and they began to cross the deep pit of the Huizhong Road tunnel and enter the area near the National Stadium and the Olympic Sports Center Natatorium, only 500 meters away from the second line of defense. A small number of zombies deviated from the direction and moved west away from the zombie herd, entering the seventh area of the south lane of the Science Park.

The zombies that left in the group of corpses added a lot of variables to the defenders, and Xu Yongping had to send a team of 50 people to keep an eye on them. Unit 61889 currently does not have enough strength to eliminate these outlier zombies, and the task of the dispatched team is to observe the movements of the zombies and warn Xu Yongping and the research institute in time.

The road in front of the National Convention Center is lined with half-height barricades, which can be used as shelter for the garrison troops and to block the advance of the zombie hordes. There were still flags fluttering on the three flagpoles in front of the conference center, and the five-star red flag in the middle was particularly dazzling, and many soldiers looked at it a few times intentionally or unintentionally, and the belief in their hearts was also a little firmer.

The fire in the Huizhong Road tunnel has been extinguished, and the average number of zombies in the zombie group has crossed the first line of defense, and the zombies in the pit are scrambling to step on the bodies of others and climb up, and a few zombies have climbed out of the pit and joined the team that continues to march north.

Xu Yongping was waiting, and now was not the best time to detonate the explosives that were placed there. In order to make all the arrangements work out in the best possible way, he has always been highly focused, and his brain has been grinding the calculations. There are few cards in his hand, which is not enough for him to win this war, but this does not prevent him from striving for strategic victory. All kinds of first-hand arrangements and arrangements have achieved unexpected results, and have bought a lot of extra time for the whole operation.

The front of the corpse group arrived near the road roller skating square, and the soldiers on the second line of defense could already clearly see the entire figure of the zombie at the front of the corpse group. They came out of the rain of bullets, almost all of them were completely skinless, some of the zombies were still burning with green smoke, and some of the zombies' bodies were no longer complete, but they just walked forward silently, no one knew where their final destination was.

A crowd of 60,000 corpses covered all the flat ground that could be seen in the field of vision, and some zombies entered the building, and the corpses were crowded one after another. Some of the warriors who had not been through the first line of defense were stunned by the sight, everyone here had fought and lost, but not all of them had fought so many zombies.

Xu Yongping and the officers seized the last time before the war and began to do mobilization and encouragement work. After a moment of absence, these soldiers regained their previous confidence, and the idea of defending the country was deeply rooted in the marrow of each of them, so after a simple mobilization, their morale was restored to the same as before.

"With the North Road of the National Stadium as the boundary, the zombie group approached within 20 meters, all the staff opened fire, and the engineering team detonated the preset explosives." Xu Yongping looked at the zombie group in front of him and gave an order.