After several stellar cycles of careful observation and research, our scientists had determined that humanity's most primal and debilitating fear was of darkness.
Many of us hypothesised that this was a vestigial, irrational fear that originated from their shared evolutionary ancestry with several herbivorous prey species that inhabited Earth.
From there, a strategy was easily formulated and implemented to ensure that humanity was not in the way of our species' progress.
Three stellar cycles before we landed, we began to disrupt their crude electromagnetic communications network.
Two stellar cycles before we landed, our engineers released microfilaments into the atmosphere to fatally damage their primitive power distribution grid.
One stellar cycle before we landed, we collapsed Earth's star.
There was a vocal minority of us who did not even think it necessary to release the Pathogen; in their collective rictus of terror, humanity, like the cornered beasts they were,
had begun to lash out, and with our ships safely out of weapons range, they began to turn on each other.
In a short amount of time, humanity had passed from the terrifying darkness of their own planet to the crushing black of death.
Earth, we thought, was ripe for the picking.
One stellar cycle after we landed, we began to receive reports from our scouting parties that defied belief and made little sense to our scientifically- and analytically-inclined minds.
Two stellar cycles after we landed, our security patrols and mining teams began broadcasting garbled, delirious distress calls, before returning wide eyed and babbling,
or going missing without a trace.
Three stellar cycles after we landed, we encountered Them.
It was only after that, that we understood the two greatest mistakes we had made.
Our first mistake was our refusal to believe that humanity had a perfectly good reason to be afraid of the dark.
Our second mistake was our assumption that Earth truly belonged to humanity in the first place.