Collision course

In this version of a possible future for mankind, a wonderful faster-than-light space drive has been invented and it works far better than expected. The entire universe appears to be open for mankind to colonize and the leaders are all in agreement with that goal. However, the experimental FTL ship returns with news of an alien civilization that was being installed on the world that had been their target destination. The ship is sent back out with negotiators who wish to avoid a colonization war. The aliens aren't in the negotiating mood...and from that point things get really interesting.