This is a brief overview of historical warfare and recent developments in Iceland. Iceland has never participated in a full-scale war or invasion and the constitution of Iceland has no mechanism to declare war. Settlement and commonwealth In the period from the settlement of Iceland, in the 870s, until it became part of the realm of the Norwegian King, military defences of Iceland consisted of multiple chieftains (Goðar) and their free followers (þingmenn, bændur or liðsmenn) organised as per standard Nordic military doctrine of the time in expeditionary armies such as the leiðangr. These armies were divided into units by the quality of the warriors and birth. At the end of this period the number of chieftains had diminished and their power had grown to the detriment of their followers. This resulted in a long series of major feuds known as Age of the Sturlungs in the 13th century. During and before the war more than 21 fortresses were built. The battle consisted of little less than 1000 men with the average casualty rate of 15%. This low casualty rate has been attributed to the blood-feud mentality that permeated Icelandic society, which meant that the defeated army could not be slaughtered honourably to a man. As well as the requirements of Christianity to get a pardon from a cleric for each fiend smitten, which resulted in only people of low class taking care of executions. While executions after battle were uncommon, they were extensive when they happened. See, for instance the battle of Haugsnes with about 110 fatalities, Flóabardagi with about 80 fatalities on one side and unknown on the other and the battle of Örlygsstaðir with up to 60 fatalities including executions. These three battles, or skirmishes as they would be called in a European context add up to 250 fatalities, so these three encounters alone add up to almost 6 of the average killings of 7 per year in the period 1220–1262. Years could pass without killings. Amphibious operations were important parts of warfare in Iceland in this time, especially in the Westfjords, while large naval engagements were not common. The largest of these was an engagement of a few dozen ships in Húnaflói known as Flóabardagi. One side employing smaller longships as well as boats and the other large Knaars, other larger merchant ships and ferries. Although neither side expected to do battle at sea, the battle