Gustavus Adolphus (9/19 December 1594 – 6/16 November 1632, O.S./N.S.), also known in English as Gustav II Adolf or Gustav II Adolph, was the King of Sweden from 1611 to 1632, and is credited for the rise of Sweden as a great European power (Swedish: Stormaktstiden). Under his sagacious leadership, Sweden emerged as one of the premier military forces on the continent during the Thirty Years' War, helping to determine the political as well as the religious balance of power in Europe. He was formally and posthumously given the name Gustavus Adolphus the Great (Swedish: Gustav Adolf den store, Latin: Gustavus Adolphus Magnus) by the Riksdag of the Estates in 1634.
He is often regarded as one of the greatest military commanders in modern history, with innovative use of combined arms. His most notable military victory was the Battle of Breitenfeld (1631). With a superb military machine, good weapons, excellent training, and effective field artillery, backed by an efficient government that could provide necessary funds, Gustavus Adolphus was poised to make himself a major European leader. He was killed a year later, however, at the Battle of Lützen (1632). He was assisted in his efforts by Count Axel Oxenstierna, the Lord High Chancellor of Sweden, who also acted as regent after his death.
In an era characterized by almost endless warfare, Gustavus Adolphus inherited three simultaneous and ongoing wars of his father at the age of sixteen. Two of these were border wars with Russia and Denmark, and a more personal war (at least for his father) with Gustavus' first cousin, King Sigismund III Vasa of Poland. Of these three wars that were passed onto his rule, the Danish war was the most acute one.
During his reign, Sweden rose from the status of a Baltic Sea basin regional power to one of the great powers of Europe and a model of early modern era government. Gustavus Adolphus is famously known as the "father of modern warfare", or the first great modern general. Under his tutelage, Sweden and the Protestant cause developed a number of excellent commanders, such as Lennart Torstensson, who would go on to defeat Sweden's enemies and expand the boundaries and the power of the empire long after Gustavus Adolphus's death in battle. Spoils meant he became a successful bookraider in Europe, targeting Jesuit collections.
Called "The Golden King" and "The Lion of the North", he made Sweden one of the great powers of Europe, in part by reforming the administrative structure. For example, he began parish registration of the population, so that the central government could more efficiently tax and conscript the people. Historian Christer Jorgensen argues that his achievement in the field of economic reform, trade, modernization, and the creation of the modern bureaucratic autocracy was as great as his exploits on the battlefields. His domestic reforms, which transformed a backward, almost medieval economy and society, were in fact not only the foundations for his victories in Germany, but also absolutely crucial for the creation and survival of the Swedish Empire.
He is widely commemorated by Protestants in Europe as the main defender of their cause during the Thirty Years' War, with multiple churches, foundations and other undertakings named after him, including the Gustav-Adolf-Werk. He became a symbol of Swedish pride.