Not Following The Script
Keelan, Millie, and the rest of the members that were tasked to rescue the Princess, boarded the Battleship of the Earldom of Draycott which was named Starlight.
According to the Captain, the Earl made the decision of making his own Battleship in order to protect his territory from Pirates while looking at a star-studded sky. Because of this, he had given the ship the name Starlight, so that even on the darkest nights, the stars would guide the battleship back home.
Lux, on the other hand, didn't board the battleship. Instead, he rented another ship docked at the Port to act as his own transport during the battle that would be waged on the high seas.
Since Keelan was in charge of the operation, it would limit Lux's own actions when it came to ordering his Undead Army, so he decided to ride a separate ship, which would let them use a pincer attack against their target out in the open sea.