Task: Question Generation
Input (English): Passage: The battle that took place on 26 July 1566 during the Northern Seven Years' War and was a slight victory for a Swedish fleet over a combined Danish and Lübecker fleet. It began just east of Öland and the Allied fleet eventually retreated toward Gotland. Two days after the battle a storm sank fourteen of the Allied ships while they were anchored near Visby, drowning around 5900 men. The Swedish fleet, further out to sea, returned to port with some damage. On 25 July, Horn discovered the Allied Danish-Lübeck fleet at the northern tip of Öland, headed for Gotland. Horn, who had a headwind, decided to avoid battle, but when the wind turned he started the battle on the morning of 26 July. A few more losses did not affect either fleet, when a sudden wind made it impossible for the Swedish navy to continue its pursuit of the Danish fleet, which was anchored to the Gotland coast to bury the Danish vice-admiral Christopher Morgisen on hallowed ground after his death from a cannonball. Shortly after that a sudden storm broke out. The Swedish navy, which was at sea, survived without major losses, other than having had to fell the main mast of the Hector, and was able to flee to Älvsnabben by 6 AUgust. The Allied fleet however was thrown against the coast of Gotland, and 12 Danish and 3 Lübeck vessels were smashed, and most of the ships' crews, numbering around 5000, were drowned, with only around 1400 surviving ashore.
Output (English): How many vessels in the Allied fleet were destroyed in all in the storm?