My Mortalen empire started good, but colonizable worlds are very rare. I found one with decent rating and started working hard to research technology to improve it enough for the breakpoint.
Finally, I managed to get it there and build a colony ship with 30 million Mortalen from my home world. I colonized the planed Rhudus 4. But just a month after that, the colony was struck with the Shakturi virus. A week after the virus had struck, they revolted, and shortly after that the declared independence from the oppressive Mortalen (yeah yeah).
At this time, I did not have any ground troops or transports. Instead, I started working to get them back into the empire the diplomatic way with bribes. Meanwhile I did find another suitable world and colonized it.
I wooed Rhudus 4 with gifts and trade deals and they liked me a lot. Everything looked good when suddenly Rhudus 4 Was invaded by my neighbor empire, the evil humans.
So I worked hard to colonize a world, then they revolted 45 days later and finally was invaded or joined the evil human empire. Moral of the story: Don't send plague struck colonists to a new world. And have the dropships ready! It was a really fun event in my game, despite it sucked for my empire.