First Contact

138 Years Before Succession, New Standard Calendar
A very large ship of inhuman origin is briefly seen entering Rhineland controlled space. Seemingly ancient, it nevertheless is very much active and corrects course and crosses the system at unheard of speed. It spends nearly two days having come to a stop near Mons Dinaric (terrifying those onboard) before "kinda shrinking" and disappearing.
That same ship appeared beyond lunar orbit around Earth not long after, though no one in the Solar system was even aware of the sighting in Rhineland at the time.
Communications were opened for the first time by radio 19 days later, though initial translation was weak and conversation was extremely limited. It became apparent that the ship belonged to a very old kind of machine built by alien intelligence, and its kind had been maintaining a defensive perimeter around Sol and its surrounding systems as a kind of nature preserve for worlds with evolving life. However, due to our expansion beyond the borders of that preserve, we had violated one of the conditions to be recognized as a preservation world. Our preservation status would expire in roughly 6 Earth years, after which our interstellar neighbors would be free to contact us, or attack us, as they saw fit.
This, understandably, resulted in panic and confusion across Sol.
The machine race, which we now call the Intercessors, offered a 'common solution'. While we could not return to our status as a preservation world, we could instead join into an agreement with them and join their established Protectorate. We would be bound by the Protectorate's laws, but under the Protectorate the Intercessors would be required to assist in the defense of any star system that was registered as human-controlled against any outside threat, and to make available certain technologies for the safety of ourselves and those around us.
Seeing little choice but to accept, we did. The Intercessors were happy to oblige, however they could not actually initiate the registration process with a species with active preservation status. They regretfully informed us that they would have to wait to begin until our preservation status expired naturally. Once the registration request was submitted, they would have to wait for approval from one of their creators, a process that would take a few days if any of them were still alive. Unfortunately, the creators of the machines had expired a long time ago. But the machines could complete the registration for the protectorate themselves as an interim approval after the request for approval from their masters passed a seven month window. During that 7 month period they would be unable to help us, as we fell into neither protected category.
They apologized for the inconvenience, and explained to us the rules of registration that would define the Contact War.