Swedish Empire
The history of Sweden between 1611 and 1721
The Swedish Empire refers to the Kingdom of Sweden's territorial control of much of the Baltic region during the 17th and early 18th centuries, a time when Sweden was one of the great European powers. The beginning of the Empire is usually taken as the reign of Gustavus Adolphus, who ascended the throne in 1611, and the end as the loss of territories in 1721 following the Great Northern War. In Swedish, the period is called Stormaktstiden, literally meaning "the Great Power Era".
After the death of Gustavus Adolphus in 1632, the empire was, over lengthy periods, controlled by part of the high nobility, most prominently the Oxenstierna family, acting as tutors for minor regents. The interests of the high nobility contrasted with the uniformity policy, i.e., the upholding of the traditional equality in status of the Swedish estates favoured by the kings and peasantry. In territories acquired during the periods of de facto noble rule, serfdom was not abolished, and there was also a trend to set up respective estates in Sweden proper. The Great Reduction of 1680 put an end to these efforts of the nobility and required them to return estates once gained from the crown to the king. Serfdom, however, remained in force in the dominions acquired in the Holy Roman Empire and in Swedish Estonia, where a consequent application of the uniformity policy was hindered by the treaties by which they were gained.
After the victories in the Thirty Years' War, the climax of stormaktstiden was reached in the Second Northern War, when the primary adversary Denmark was neutralized by the Treaty of Roskilde in 1658. However, in the further course of this war as well as in the subsequent Scanian War, Sweden was able to maintain her empire only by support of her closest ally, France. Charles XI of Sweden consolidated the empire and ensured a period of peace, before Russia, Saxony and Denmark started a concerted attack on his successor, Charles XII. After initial Swedish victories, Charles secured the empire for a last time in the Peace of Travendal (1700) and the Treaty of Altranstädt (1706), before the Battle of Poltava (1709) brought the stormaktstiden of Sweden to a sudden end.
References: Wikipedia