When the Skulls returned to finish off the island’s people, they found a force waiting for them that was more powerful than anything they ever faced. All but one of their ships were sent to the bottom of the ocean. The one surviving ship escaped with enough of its crew to get back to their base. They did not know the Maids of Merr were following them for the purpose of wiping out their nest.
The Maids of Merr took over the ship when it arrived at its harbor. They used the cannons of the captured ship to sink six Skull ships in their docks, then let the rest chase them into open waters. Once they were in the ocean, the Maids of Merr used their Mermaid spell to wipe out the crews and send the ships to the bottom of the ocean.
The Maids of Merr discovered the destruction of the Skulls was not enough to restore peace. To put a stop to the threat of the Skulls, they had to locate their origin and chop off the heads of the underworld witchcraft that spawned them.