The main tendencies in the development of Scandinavian political organisation in the high Middle Ages were centralisation and growth of public authority under the monarchy, the Church, and the secular aristocracy. This chapter outlines the development of three Nordic kingdoms that grew into more state-like entities, until 1319 when the first of the Nordic unions was established between Norway and Sweden. Danish struggles over the succession to the throne from the 1130s to the 1150s were followed by the strong and expansionist Valdemarian monarchy which once more made Denmark the leading kingdom in Scandinavia. In Norway, the Norwegian church was centralised under the archbishop of Trondheim in 1152-3, and in the following decades the first steps were taken towards a nationally organised system of government. Scandinavian kingship entered a new phase in the high Middle Ages, reflected by the introduction of royal unction and coronation. There may have been early royal initiatives in provincial thing legislation in the Scandinavian kingdoms.

The Black Death struck the whole of Scandinavia except Iceland; in Norway, in particular, its effects were aggravated by subsequent epidemics, smallpox in 1359-60, plague in 1371. In the political history of the Scandinavian countries, Denmark, Finland, Iceland and the states of the Scandinavian peninsula, Norway and Sweden, the long fifteenth century from c.1390 to the Reformation forms a well-defined period. In Sweden, the resumption of alienated crown lands had aroused the opposition of the Church. The Great Schism having undermined the authority of the Papacy, the general council emerged as the leading ruling body of the Church. Sweden had deposed Erik and was ruled by Karl Knutsson as regent. In the winter of 1439-40 Erik concluded an alliance with the overlord of the Low Countries, Duke Philip of Burgundy. The battle of Brunkeberg was a turning-point in Scandinavian history. The riksråd, convoked to meet on 30 October, declared on the following day that Christian was lawful heir to Sweden.