After Gulliver brought the ships to King Golbasto, the king told him to go back and get the rest of the ships. Why?

This question refers to events that unfold in chapter 5 of Jonathan Swift's satirical novel Gulliver's Travels. The main thing you need to be aware of when discussing this subject is that Lilliput is opposed by a rival empire, Blefuscu. Gulliver's capture of the ships actually refers to his capture of an enemy fleet.
With his victory, however, Gulliver has also dramatically demonstrated the degree to which he provides Lilliput with an almost insurmountable military advantage over its rival. The Emperor of Lilliput wishes to exploit that advantage. He demands that Gulliver endeavor to bring him all of Blefescu's ships, but the important thing to keep in mind is that the emperor's ultimate aim here is to conquer Blefuscu by force. He wishes to use the comparatively huge and powerful Gulliver in order to subjugate this rival power. Gulliver is awarded a title and a place in the Lilliputian court for his service but is later sentenced to death for urinating on a fire in the palace. From there, Gulliver ends up fleeing to Lilliput's enemy nation, Blefuscu.