Part 1: The War

It's the year 2286. The United Earth Union (UEU) united the earth 92 years earlier. If only the UEU would know what would happen 23 years after their founding...
The 7th of April 2248 was when everything changed for earth. The first invasion. Now they're known as the Ulgari, back then, we only knew them as the aliens or the invaders. They gave us no warning. Major civilian zones were destroyed in a matter of days. It's not like the population had the firepower to do anything about this and because of the demilitarization of earth, the army wasn't prepared either. We still had to defend ourselves. It started with with the military we had, supplemented by what we had in museums. Luckily, we still had plenty of technology that had advanced, getting that militarized was the challenge.
We still fended them off eventually... At an enormous cost of human life. We decrypted their plans, and this was only a scout group. If we didn't strike back, they would send larger waves. We were sure we'd not be able to survive so we started the Universal Draft. Any non-essential humans were drafted into the army, preparing them to fight on the front lines. The plan was simple. Take out their spaceships and factories. It took a full 2 years to manage that, but we did it, but we also noticed that they were resilient. Not only did they keep fighting back, but they also kept trying to create new ships.
We've kept the pressure on them by assaulting their planet. This has kept earth earth safe for now...