You return to Sentinel Hill. At the sight of its gnomishly-enhanced buttresses, the scaredy-cat goblin pursuers turn tail. Alarmed at the return of the Defias, the Marshal allows you to improve the Hill's defenses, finally recognizing your technological genius. The improvement project is interrupted when Kearnen spots a giant ship going by on the horizon. The Marshal demands you stop it, and lo and behold, who is commanding the ship but a goblin! He however disavows all responsibility in typical goblin fashion, so you do a nice turn in your tank, roll down to the south through where those of your pursuers unfortunate enough to be on the doomed ship were before the ship launched, and blow up his boss.
Case closed.