A few years prior to the recent events of Kirby: Planet Robobot, Meta Knight had an idea.
Dedede was not a productive king at the time and Meta Knight wanted Dreamland to be prepared for an attack against the planet, so, he and his men hired a construction crew with experience in constructing ships for warfare.
Within a year, the Halberd was built, and placed within a secret base near the coastline at Orange Ocean.
A month of planning and organization passed and the Halberd was ready to roll!
However, Kirby, overheard someone talking about Meta Knight's ambition, and misinterpreted it as an actual assault against Dreamland!
He set off in a misguided attempt to put down the Halberd.
He succeeded, and a wrecked Halberd crashes into a specific part of Orange Ocean, known as Secret Sea.
A Year later, Kirby, in his quest to retrieve his stolen Strawberry Shortcake, stumbles across the apparent remains of the Ship, and investigates it.