Gustav II Adolf (9 December 1594 – 6 November 1632, O.S.), widely known in English by his Latinised name Gustavus Adolphus or as Gustav II Adolph, or as Gustavus Adolphus the Great (Swedish: Gustav Adolf den store, Latin: Gustavus Adolphus Magnus, a formal posthumous distinction passed by the Riksdag of the Estates in 1634); was the King of Sweden from 1611 to 1632 and is credited as the founder of Sweden as a Great Power (Swedish: Stormaktstiden). He led Sweden to military supremacy during the Thirty Years' War, helping to determine the political as well as the religious balance of power in Europe.
He is often regarded as one of the greatest military commanders of all time, with innovative use of combined arms. His most notable military victory was the Battle of Breitenfeld. With a superb military machine with good weapons, excellent training, and effective field artillery, backed by an efficient government which could provide necessary funds, Gustavus Adolphus was poised to make himself a major European leader, but he was killed at the Battle of Lützen in 1632. He was ably 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, he led his armies as king from 1611 (at age 16) until his death in battle in 1632 while leading a charge - as Sweden rose from the status of a mere regional power to one of the great powers of Europe and a model of early modern era government. Within only a few years of his accession, Sweden had become the largest nation in Europe after Russia and Spain. Some have called him 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' death in battle.
He was known by the epithets "The Golden King" and "The Lion of the North" by neighboring sovereigns. He made Sweden one of the great powers of Europe in part by reforming the administrative structure.