on 16 july 1627, the islands were captured by a group of north african pirates who stayed there until 19 july. they were under control of the ottomans. the pirates captured 234 people from the islands and took them on a 27-day voyage to algiers, where most of them spent their life under bondage. one of the prisoners, minister ólafur egilsson, returned in 1628 to the islands and wrote a book about his experience. in 1636, a ransom was paid for 34 of the captives, and most of them returned to iceland. after this, a fort was built on the helgafell volcano to keep watch for ships.