Echo One had their com-links cut by a Volterite EMP - as they were heading to Kappa Sector to fix some sensor arrays they were ambushed by Volterites
Kal Wardin and Echo One then pushed to attack the Volterite's signal jammer to get comlinks back online so Actual could see enemy strength.
As they approach the jammer itself inside the building - Kal starts shutting it down. As he does so, a wounded volterite activates a bomb and blows up - launching Kal into the air and destroying the Jammer.
After the explosion - The squad regroups and decides to "hoof it" back to base.
After battling through Volterite forces in an underground parking-lot and street the squad splits up, Wilcox and Sergeant Becker take one tower whilst Kal and Private Chao take another in order to make the job easier.
After Private Chao and Kal fix one of the sensor arrays, they head their way to meet up with Sergeant Becker and Wilcox. During their descant of the tower, they receive contact with Actual ( Yelena ) who tells them the main base is under-attacking and they need to make their way back ASAP. Private Chao and Kal soon after regroup with Becker and Wilcox and they quickly make their way to the main base. Shortly after arriving, they meet up with Yelena ... who jumps out of a Mech to greet Kal and explain to him why Volterites are on Earth.
During the evacuation, the base comes under attack by waves of volterite forces - here is the last time you see Private Chao and Wilcox - both of whom presumably were evacuated by N.O.V.A forces. Sergeant Becker and Kal, however, stay behind to locate the judger artifact - which also works as a terraformer for dead planets. Becker and Kal both hop in a 4x4 combat vehicle, with Becker taking the wheel whilst Kal rides back with a machine gun.
The two fight their way on the road toward the location of the Artifact. Upon arrival, Kal hops out of the 4x4 and orders Sergeant Becker to "Stay on the gun", this is the last time Becker is seen. Later in the location of the artifact - Prometheus explains to Kal that Becker was KIA.