The name Skansinn is Danish for "fort". The oldest reference for a fort on this location dates from 1586 when King Fredrick II. of Danes instructed his Admiralty to build a fort on a hill called Kornhóll (Cornhill) at the harbor to defend the Danish monopoly trade post against English fishing efforts and competitive trade. A small fort was built with rock and wood by the inhabitants as a community service to the king and cannons installed.
During 16.-19. July 1627 Heimaey was raided by slave hunters from Algiers, N. Africa, the event termed the "Tyrkjarántő" or the Turkish raid. Three raiding ships sailed along the east coast and beached 300 hunters which rounded up 242 of the inhabitants up in the Danish trade houses, killing and raping people alongside. The route to the harbor was now open and the people were transferred onboard, already containing Icelanders kidnapped from the eastern parts. As the course was set to a slave market in Algiers the flames from Danish trade houses and Landakirkja were visible.
The reconstruction of Skansinn begun in 1630 and took eight years, but it has been improved many times since. The fort was armed with up to six cannons and had a residing master guard, which maintained the weapons and trained their use. The best known guard was Jón Ólafsson Indiafari (1639). Two sentinels were put on top of Helgafell Mountain guarding the ship traffic from spring to fall. In case of suspicious ship traffic one was supposed to run to Landakirkja and ring the church bells, the other to the fort. This surveillance terminated about 1700. In 1853 the Danish Captain Andreas August von Kohl (1815-1860) was hired to the Westman Islands as the Marshall.
Together with the local Merchant Peter Bryde they enlarged the fort substantially by elevating its wall and building a broad inner platform on the north and east sides. Captain Kohl founded the Westman Islands Militia, but its main purpose was defenses against foreign attack, local police, fight the vices of alcohol, and to generally enlighten its members. The Militia was one of the first domestic sport organizations. Practices were frequent and the Militia counted 104 men in 1859. It was discontinued in 1869 but its influences lured for long. During WWII the local British army had its Headquarters and a cannon nest in Skansinn.
The fort's walls were rebuilt in 1991-1992. In 1997, 370 years after the Tyrkjaránið, Ísfélag Vestmannaeyja Inc. gave the cannon which is currently installed. It is fired on special occasions.
Source: Local signage