Frederick Augustus I or Augustus II the Strong (German: August II der Starke; Polish: August II Mocny; Lithuanian: Augustas II; 12 May 1670 – 1 February 1733) was Elector of Saxony (as Frederick Augustus I) and King of Poland and Grand Duke of Lithuania (as Augustus II).

Augustus's great physical strength earned him the nicknames "the Strong," "the Saxon Hercules" and "Iron-Hand." He liked to show that he lived up to his name by breaking horseshoes with his bare hands and engaging in fox tossing with a single finger. His ancestor Cymburgis of Masovia was also noted for her strength. Augustus the Strong owed allegiance to the Imperial Habsburgs as a member of the Order of the Golden Fleece. As Elector of Saxony, he is perhaps best remembered as a patron of the arts and architecture. He established the Saxon capital of Dresden as a major cultural centre, attracting artists and musicians from across Europe to his court. Augustus also amassed an impressive art collection and built fantastic baroque palaces at Dresden and Warsaw. As a politician, he is nowadays held in low esteem in Poland, in particular for his role in embroiling the Polish - Lithuanian Commonwealth in the Great Northern War. His attempts at internal reforms and at bolstering the royal power are considered failures, while his policies are thought to have allowed the Russian Empire to strengthen its influence over the Polish - Lithuanian Commonwealth.

Augustus was born in Dresden, the second and youngest son of the Elector Johann Georg III and Anne Sophie of Denmark. As the second son, Augustus had no expectation of inheriting the Electorate, since his older brother, Johann Georg IV, assumed the post after the death of their father on 12 September 1691. Augustus married Christiane Eberhardine of Brandenburg - Bayreuth in Bayreuth on 20 January 1693. They had a son, Frederick Augustus II (1696 – 1763), who succeeded his father as Elector of Saxony and King of Poland as Augustus III. While disporting himself during the carnival season in Venice, his older brother, the Elector Johann Georg IV, contracted smallpox from his mistress Magdalene Sybille of Neidschutz. On 27 April 1694 Johann Georg died without legitimate issue and Augustus became Elector of Saxony, as Frederick Augustus I.

In order to be eligible for the throne of the Polish - Lithuanian Commonwealth, Augustus had to convert to Roman Catholicism. The Saxon dukes had traditionally been called "champions of the Reformation." The duchy had been a stronghold of German Protestantism and Augustus's conversion was therefore considered shocking in Protestant Europe. The electors of Saxony had to cede its prestigious role as leader of the Protestant Estates in the Imperial Diet (see Reichstag) to Brandenburg - Prussia. Since the prince elector guaranteed Saxony's religious status quo, Augustus's conversion alienated many of his Protestant subjects. As a result of the enormous expenditure of money used to bribe the Polish nobility and clergy, Augustus's contemporaries derisively referred to the Saxon duke's royal ambitions as his "Polish adventure."

It is noteworthy that the directorate of the Corpus Evangelicorum, which was the official Imperial board of the Protestant Estates and the counterpart of the Corpus Catholicorum, remained under Saxon auspices with the Roman Catholic Augustus, paradoxically, at its head. His church policy within the Holy Roman Empire followed orthodox Lutheranism and ran counter to his new found religious and absolutist convictions. The Protestant Princes of the Empire and the two remaining Protestant Electors (of Hanover and Prussia) were anxious to keep Saxony well-integrated in their camp. According to the Peace of Augsburg, Augustus theoretically had the right to re-introduce Roman Catholicism (see Cuius regio, eius religio), or at least grant full religious freedom to his fellow Catholics in Saxony, but this never happened. Saxony remained Lutheran and the few Roman Catholics residing in Saxony were without any political or civil rights. In 1717 it became clear just how awkward the situation was: to realize his ambitious dynastic plans in Poland and Germany it was necessary for Augustus's heirs to become Roman Catholic. After five years as a convert, his son — the future Augustus III — publicly avowed his Roman Catholicism. The Saxon Estates were outraged and revolted. It was becoming clearer that the conversion to Roman Catholicism was not only a matter of form, but of substance as well.

The wife of Augustus I, the Electress Christiane Eberhardine, refused to follow her husband's example and remained a staunch Protestant. She did not attend her husband's coronation in Poland and led a rather quiet life outside of Dresden, gaining for herself some popularity and notoriety for her stubbornness.

Following the death of Polish King John III Sobieski and having successfully converted to Catholicism, Augustus was elected King of the Polish - Lithuanian Commonwealth in 1697 with the backing of Imperial Russia and Austria, which financed him through the Jewish banker, Berend Lehmann. It is sometimes incorrectly stated that Augustus "defeated" the other leading candidates, Jakub Ludwik Sobieski, son of the previous king, and the French candidate, François Louis, Prince of Conti. Augustus actually received fewer votes than Conti (despite a massive bribery campaign), but he rushed to Poland and had himself crowned before the French candidate could set foot in the Commonwealth. Some Poles questioned the legality of Augustus's elevation.

He continued the war of the Holy League against Turkey, and after a campaign in Moldavia his Polish army eventually defeated the Tatar expedition in the Battle of Podhajce in 1698. This victory compelled the Ottoman Empire to sign the Treaty of Karlowitz in 1699. Podolia and Kamieniec Podolski returned to Poland.

An ambitious ruler, Augustus hoped to make the Polish throne hereditary within his family, and to use his resources as Elector of Saxony to impose some order on the chaotic Polish - Lithuanian Commonwealth. He was, however, soon distracted from his internal reform projects by the possibility of external conquest. He formed an alliance with Denmark's Frederick IV and Russia's Peter I to strip Sweden's young King Charles XII (who incidently was Augustus's cousin) of his possessions. Poland's reward for participation in this Great Northern War was to have been the Swedish territory of Livonia. Charles proved an able military commander, however, quickly forcing the Danes out of the war and then driving back the Russians at Narva, thereby allowing him to focus on the struggle with Augustus. Charles's decision ultimately proved as disastrous for Sweden as for Poland.

Charles defeated Augustus at Riga on 17 June 1701, forcing the Polish - Saxon army to withdraw from Livonia, and followed this up with an invasion of Poland. He captured Warsaw on 14 May 1702, defeated the Polish - Saxon army again at the Battle of Kliszów, and took Kraków. He defeated another of Augustus's armies under command of Generalfeldmarschall Adam Heinrich von Steinau at the Battle of Pułtusk in spring 1703, and besieged and captured Thorn (Toruń).

By this time, Augustus was certainly ready for peace, but Charles felt that he would be more secure if he could establish someone more pliable on the Polish throne. In 1704 the Swedes installed Stanisław Leszczyński and tied the commonwealth to Sweden, which compelled Augustus to initiate military operations in Poland alongside Russia (an alliance was concluded in Narva summer 1704). On 1 September 1706, Charles invaded Saxony, forcing Augustus to yield the Polish throne to Leszczyński by the Treaty of Altranstädt.

Meanwhile Russia's Tsar Peter the Great had reformed his army, and dealt a crippling defeat to the Swedes at the Battle of Poltava. This spelled the end of the Swedish Empire and the rise of the Russian Empire.

The weakened Polish-Lithuanian Commonwealth soon came to be regarded almost a protectorate of Russia. In 1709 Augustus II returned to the Polish throne under Russian auspices. Once again he attempted to establish an absolute monarchy in the Polish - Lithuanian Commonwealth, but was faced with opposition from the nobility (szlachta, Tarnogród Confederation). Peter the Great seized on this opportunity to pose as mediator, threatened the Commonwealth militarily, and in 1717 forced Augustus and the nobility to sign an accommodation favorable to Russian interests, at the Silent Sejm (Sejm Niemy).

For the remainder of his reign, in an uneasy relationship, Augustus was more or less dependent on Russia (and to a lesser extent, on Austria) to maintain his throne. After the Silent Sejm, he gave up his dynastic ambitions and concentrated instead on attempts to strengthen the Polish - Lithuanian Commonwealth. Faced with both internal and foreign opposition, however, he achieved little.

Augustus died at Warsaw in 1733. Although he had failed to make the Polish throne hereditary in his house, his eldest son, Frederick Augustus II of Saxony, did succeed him to the Polish throne as Augustus III of Poland — although he had to be installed there by a Russian army in the War of the Polish Succession.

Augustus II was called "the Strong" for his bear-like physical strength and for his numerous offspring (only one of them his legitimate child and heir). The most famous of the king’s children born out of wedlock was Maurice de Saxe, a brilliant strategist who attained the highest military ranks in the kingdom of France. In the War of the Polish Succession he remained loyal to his employer Louis XV of France, who was married to the daughter of Augustus’s rival Stanisław Leszczyński. August was 1.76 meters (5’ 9½”) tall, above average height for that time, but despite his extraordinary physical strength he did not look big. In his final years he suffered from diabetes mellitus and became obese, at his death weighing some 110 kg (242 lbs). August II's body was interred in Poland — all but his heart, which rests at Dresden's Katholische Hofkirche.

In Warsaw, the Saxon Garden (Polish: Ogród Saski) commemorates the role of August II in expanding the city's public places.

Augustus loved fine arts and architecture, and he had beautiful palaces built in Dresden, a city that became renowned for extraordinary cultural brilliance. From 1687 to 1689 Augustus toured France and Italy. The extravagant court in Versailles -- perfectly tailored to fit the needs of anabsolute monarch -- impressed him deeply. In accordance with the spirit of the baroque age, Augustus invested heavily in the representative splendor of his residence to advertise his wealth and power. With strict edificial regulations, major urban development plans, and a certain feeling for art, the king began to transform Dresden into a renowned cultural center with one of Germany’s finest art collections, though most of the famous sights and landmarks of Dresden were completed during the reign of his son Augustus III. The most famous building that was started during his reign was the Zwinger. Being a man of pleasure, the king sponsored lavish court balls, Venetian style balli in maschera, and luxurious court gatherings, games, and garden festivities. His court acquired a reputation for extravagance throughout Europe.

Augustus II successfully sponsored efforts to discover the secret of manufacturing porcelain. In 1701 he rescued the young alchemist Johann Friedrich Böttger, who had fled from the court of the king of Prussia, Fredrick I, who had expected that he produce gold for him as he had boasted he could. King Augustus II imprisoned Böttger and tried to force him to reveal the secret of manufacturing gold. Böttger's transition from alchemist to potter was orchestrated as an attempt to avoid the impossible demands of the king. Being an alchemist by profession rather than a potter gave Böttger an advantage. He realized that the current approaches which involved mixing fine white substances like crushed egg shells into clay was not the answer. Rather, his approach was to attempt to bake clay at higher temperatures than had ever before been attained in European kilns. That approach yielded the breakthrough that had eluded European potters for a century. The manufacture of fine porcelain continues at the Meissen porcelain factory.