Destruction of Project P.E.G.A.S.U.S.

"We have no quarrel with your people." "An ant has no quarrel with a boot."

- Nick Fury and Loki

The Destruction of Project P.E.G.A.S.U.S. was the battle that started the War for Earth. The outcome of the battle was the complete destruction of almost all the work done in Project P.E.G.A.S.U.S. and Hawkeye, Erik Selvig, and other S.H.I.E.L.D. agents getting their minds controlled by Loki.

Background
After the events in Puente Antiguo, New Mexico, the World Security Council ordered Nick Fury to divert the majority of S.H.I.E.L.D. resources into Project P.E.G.A.S.U.S., a program designed to create weapons based on the Tesseract

Loki was defeated by Thor and fell into Yggdrasil itself, transporting him to the Chitauri Space. Loki came into contact with the Other, a servant of Thanos, who offered a pact that would allow him to become ruler of the Earth while Thanos would take the Tesseract. Thanos gave Loki control of the Chitauri and provided him with the Chitauri Scepter that was powered by the cube itself. It acted as a very powerful weapon, and also as a mind control device, bending those who were touched by the gem's power to its will.

Accepting the deal without fear of failure, Loki turned his focus back to Earth in search of a suitable agent, someone close to the Tesseract. He found Erik Selvig, a friend of Thor's and a renowned astrophysicist, who had been summoned to the task of unlocking the secrets of the mysterious cube. In time, Selvig came to understand some of the Tesseract's capabilities, and through Loki's influence, he developed equipment that would focus some of that power.

Battle
"Dr. Selvig read an energy surge from the Tesseract four hours ago." "NASA didn't authorize Selvig to go to test phase." "He wasn't testing it, he wasn't even in the room. Spontaneous event."

- Phil Coulson and Nick Fury

When the time was right, Loki activated the Tesseract, forming a temporary portal that pulled him to its location on Earth. Despite Nick Fury asking him to lower the scepter, but Loki attacked without answering, killing many of the S.H.I.E.L.D. agents securing the room. However, he decided to spare Hawkeye's life, mind-controlling him to gain his assistance, and went to control other agents.

Fury tried to leave with the Tesseract, and while politely asking him not to leave, Loki introduced himself as denizen of Asgard, sent with what he defined as a glorious purpose. Erik Selvig recognized Loki as Thor's brothers from the legends, and Fury tried to appease him claiming Humans had nothing against the people of Asgard. Loki gave a speech about his purpose of unifying the world under his rule and controlled Selvig.

Fury tried to stall Loki after realizing that the energy liberated by the Tesseract would collapse the room and probably the entire Joint Dark Energy Mission Facility, but Barton warned Loki about the ruse. Barton shot Fury on Loki's orders and then left with Loki and the people under Loki's thrall.

As the group left the facility, they passed by Deputy Director Maria Hill who questioned Barton about Loki's identity. After failing to receive a substantive answer and upon being warned by Fury, who survived Barton's shot, the group were enemies, Hill pursued Barton and Loki in a vehicle.

Agent Phil Coulson informed Fury of the full evacuation of the facility, and Fury himself managed to board a helicopter before the ground collapsed. Meanwhile, Barton managed to escape Hill after she was trapped by debris falling from the tunnel as it collapsed, but his vehicle was pursued and attacked by Fury's helicopter. Loki shot at the helicopter with his scepter and, although Fury was able to jump and survive its crash, he couldn't prevent Loki from finally escaping with the Tesseract.

Aftermath
Now that Loki had started a war, Nick Fury found this to be the perfect opportunity to reactivate the Avengers Initiative. One by one, Bruce Banner, Tony Stark, and Steve Rogers came together. When Thor managed to return to Earth, he joined as well.