Why do the Athenians mourn when they see the black-sailed ship in the harbor?

Fourteen of Athens young men and women will be taken to Crete and devoured by the Minotaur.

The ship comes to tell them that King Minos's son is dead.

A host of rude soldiers from Crete have come to terrorize the town.

The king of Crete has sent the Minotaur to devour fourteen young men and women of Athens.​