Unable to make peace with a minor civilization

Playing v4.1.1 of GalCiv4 on Steam.  Playing the mission Terran Alliance Ascendant.  I accidentally declared war on a minor civilization, but stopped short of destroying them.  However, even though I've wiped out the sole major civilization opponent, I haven't achieved "protecting three minor civs", even though my influence is across the galaxy.  I have no options in diplomacy to make peace with this minor civ.

Help?