Excerpts from Books and Wikipedia
"The 17th century saw the phenomenal growth of Sweden as a regional imperial power. By 1648, after victories over rivals Denmark, Poland, and Russia, it had established a Baltic empire, the high point of which was reached during the reign of Charles X (1654-60). But lacking indigenous resources, Sweden's strength rested on its control of strategic harbors and customs points around the Baltic. Defending them forced Sweden into a series of costly wars from 1655. Following the Great Northern War of 1700, much of the Swedish empire was lost to the rising powers of Peter the Great's Russia, Prussia, and Hanover." [DK Timelines, p. 297] "In 1523, after the abolition of the Kalmar Union, Gustav Eriksson (Vasa) became King Gustav I of Sweden and the royal house was founded. His reign is sometimes referred to as the beginning of the modern state of Sweden, which included the King's break with the Roman Catholic Church during the Protestant Reformation and the foundation of the Church of Sweden." [Wikipedia] "Power was concentrated in the hands of the king and hereditary monarchy came into force in 1544." [https://sweden.se/society/history-of-sweden/]