Iceland

• The Middle Ages
The Icelandic Commonwealth lasted until the 13th century, when the political system devised by the original settlers proved unable to cope with the increasing power of Icelandic chieftains. The internal struggles and civil strife of the Age of the Sturlungs led to the signing of the Old Covenant in 1262, which ended the Commonwealth and brought Iceland under the Norwegian crown. Possession of Iceland passed to the Kalmar Union in 1415, when the kingdoms of Norway, Denmark and Sweden were united. After the break-up of the union in 1523, it remained a Norwegian dependency, as a part of Denmark–Norway.
In the ensuing centuries, Iceland became one of the poorest countries in Europe. Infertile soil, volcanic eruptions, deforestation and an unforgiving climate made for harsh life in a society where subsistence depended almost entirely on agriculture. The Black Death swept Iceland twice, first in 1402–04 and again in 1494–95. The former outbreak killed 50% to 60% of the population, and the latter 30% to 50%.
Around the middle of the 16th century, as part of the Protestant Reformation, King Christian III of Denmark began to impose Lutheranism on all his subjects. Jón Arason, the last Catholic bishop of Hólar, was beheaded in 1550 along with two of his sons. The country subsequently became officially Lutheran and Lutheranism has since remained the dominant religion.