The Military history of Denmark is centered around an involvement in wars in Northern Europe since 793 and, recently, elsewhere. In the early Middle Ages, Danish Vikings invaded and conquered parts of the British Isles and Normandy. Later in the Middle Ages, Denmark was repeatedly in combat with Scandinavian neighbours and in the Baltic area. The "Union Wars" of the 15th and early 16th centuries took place between Denmark and Sweden, then united in the Kalmar Union. After Sweden broke away, Denmark – until 1814 remaining united with Norway – again confronted Sweden in the Northern Seven Years' War (1563–70) and the Kalmar War (1611–13). Denmark was heavily involved in the Thirty Years' War (1618–1648) on the side of the Protestants of the German lands. During the 16th to 18th centuries, Da