The Viking chiefs established relations with Christian monarchies and the church, especially in Normandy and England. Thus Olaf I Tryggvason, a descendant of Harald Fairhair, led a Viking expedition to England in 991. He was baptized and returned to Norway in 995, claiming to be king and recognized as such along the coast, where Christianity was already known. These areas were Christianized by Olaf, by peaceful means if possible and by force if necessary; he also sent missionaries to Iceland, where the new religion was adopted by the parliament (Althing) in 999–1000. In the same year, Olaf was killed in the Battle of Svolder. Fifteen years later another descendant of Harald Fairhair, Olaf II Haraldsson—who had returned from England—was acknowledged as king throughout Norway, including the inland areas. Olaf worked to increase royal power and to complete the Christianization of the country. In so doing, he alienated the former chieftains, who called on Canute of Denmark (now ruler of England) for help. Olaf was killed in battle with the Danes and peasant leaders at Stiklestad in 1030.

Canute’s rule in Norway soon proved unpopular with the chieftains, and, with support from the bishops, the deceased king Olaf became St. Olaf, the patron saint of Norway. With the death of Canute in 1035, Olaf’s young son, Magnus, was elected king. He was succeeded in 1047 by his uncle Harald III Sigurdsson (Harald Hardraade), a former commander of the Vikings in the imperial guard in Constantinople. Harald was killed during a vain attempt to conquer England in 1066.

The Olaf (Fairhair) kings firmly established the Norwegian monarchy with the help of English bishops. In return, sees and abbeys received the larger part of the estates that the Fairhair dynasty had confiscated from the Viking chieftains during the unification of Norway.

Conflict of church and state

Following the rule of Magnus III’s sons, the increasing power of the church and the monarch contributed to a century of civil war. During the early 12th century the kings expanded their direct rule over the various provinces, and the family aristocracy in Norway grew discontented. With the accession of Harald IV (ruled 1130–36), interest groups within Norwegian society began supporting pretenders to the throne, and the church was successful in exploiting civil unrest to win independence.

Even though Norway first was Christianized from England, the Norwegian bishops—together with the other Nordic bishops—fell under the archbishop of Bremen (Germany) in the 11th century. A Nordic archbishopric was established in 1104 in Lund (now in Sweden), probably to remove any influence from the Holy Roman emperor on the Nordic churches. In 1152–53 the English cardinal Nicholas Breakspear (later Pope Adrian IV) visited Norway, resulting in the establishment of an archbishopric in Nidaros. The Holy See decided that the new archbishopric should comprise the five bishoprics in Norway (Nidaros, Bergen, Stavanger, Oslo, and Hamar) and the six bishoprics on the western islands (Skálholt and Hólar in Iceland, Greenland, the Faroes, the Orkneys, and the Hebrides with the Isle of Man). In 1163 the church of Norway supported the claims of a pretender, Magnus V Erlingsson, in return for his obedience to the pope, guarantees for the reforms of 1152, and the issuance of a letter of privileges for the church. Magnus’s coronation was the first at which the archbishop presided. The first written law of succession, dating from this coronation, established primogeniture in principle and the prior right of legitimate royal sons to the crown. Instead of kings being elected by the things, a representation dominated by the church was to serve as the electoral body. The law was never applied, and Magnus was succeeded by Sverrir Sigurdsson, a priest from the Faroe Islands who represented himself as a grandson of Harald IV, the first pretender king. After seven years of fighting, Sverrir was acknowledged in 1184 as king of all Norway and set out to bring the church under royal control. He refused to recognize the reforms and privileges made since 1152, and the archbishop and most of the bishops went into exile; Sverrir was excommunicated. The exiles in Denmark established a rebellious party and allied themselves with the secular enemies of the king, who were opposed to the king’s administrative reforms—including the establishment of the hird as a new aristocracy composed of court officials and the heads of estates. This opposition party won control of the Oslo and inland areas and threatened Sverrir’s rule until his death in 1202.

Civil war continued until 1217, when Sverrir’s grandson Haakon IV became king, beginning the “Golden Age” of Norway. Haakon modernized the administration by creating the chancellor’s office and the royal council. He prohibited blood feuds, and a new law of succession was passed (1260) by a national assembly that established the indivisibility of the kingdom, primogeniture, the prior claim of the legitimate royal sons, and, most importantly, the hereditary right of the king’s eldest legitimate son to the crown. During Haakon’s reign relations in the northern area were first regulated by a treaty with Russia (signed at Novgorod; a similar treaty signed there went into effect in 1326). Greenland and Iceland agreed voluntarily to personal unions with the Norwegian king in 1261 and 1262, marking the greatest extent of Norwegian expansion, which included the Faroes and the Scottish isles. Haakon died during an unsuccessful expedition to the Hebrides in 1263, and in 1266 his son and successor, Magnus VI, ceded the Hebrides and the Isle of Man to Scotland in return for recognition of the Norwegian claim to the Orkney and Shetland islands.

Magnus VI earned the epithet Lawmender for his work on Norway’s legislation. During his reign (1263–80) a common national law code, with special chapters for the towns, replaced the earlier provincial laws in 1274–76. Haakon’s law of succession was confirmed, and a hereditary nobility was established. The king thus took over the legislative functions, and the thing became courts presided over by royal judges (lagmenn). Such a systematic national code, prepared in the king’s chancery, was unique in 13th-century Europe. It remained in force from the 1270s until the Norske Lov of 1687; the version of the code for Iceland (the Jónsbók, 1281) is still partly in force. In a concordat of 1277 the church of Norway had to accept the new lawbooks. Some of the privileges of the church were curtailed, but those that were confirmed left the church essentially independent within its own sphere.

Magnus was succeeded by his young son Erik II (1280–99). Erik’s regency was led by secular magnates who controlled central power throughout his reign. The church tried to win privileges that had been denied by Magnus, but the regency proved stronger. The magnates also tried to limit the rights of the German merchants in Norway but were answered by a blockade from the Hanse cities and forced to agree to the German demands. Erik was succeeded by his brother, Haakon V (1299–1319), who was determined to renew the royal power. He built a series of fortresses, including Akershus in Oslo, marking the shift of political power from the west coast to the Oslo area. Haakon was unable to restore royal power to the extent he wished, however.