information:classification
Apex and the Golden Age (1573–1648)

On 11 May 1573, Henry de Valois, son of Henry II of France and Catherine de' Medici, was proclaimed King of Poland and Grand Duke of Lithuania in the first royal election outside Warsaw. Approximately 40,000 nobles cast a vote in what was to become a centuries-long tradition of a nobles' democracy (Golden Liberty). Henry already posed as a candidate before Sigismund's death and received widespread support from the pro-French factions. The choice was a political move aimed at curtailing Habsburg hegemony, ending skirmishes with the French-allied Ottomans, and profiting from the lucrative trade with France. It was also believed that an Austrian Archduke could be too powerful and attempt to limit noble privileges. French envoys had also offered large amounts of bribes, amounting to several hundred thousand ecus. Upon ascending the throne, Henry signed the contractual agreement known as the Pacta conventa and approbated the Henrician Articles. The Act stated the fundamental principles of governance and constitutional law in the Polish–Lithuanian Commonwealth. In June 1574, Henry abandoned Poland and headed back to claim the French crown following the death of his brother and predecessor, Charles IX. The throne was subsequently declared vacant.

The interregnum concluded on 12 December 1575 when primate Jakub Uchański declared Maximilian II, Holy Roman Emperor, as the next king. The decision was condemned by the anti-Habsburg coalition, which demanded a "native" candidate, known as "Piasts". As a compromise, on 13 December 1575 Anna Jagiellon – sister of Sigismund Augustus and a member of the Jagiellonian dynasty – became the new monarch. The nobles simultaneously elected Stephen Báthory as co-regent, who ruled jure uxoris. Báthory's election proved controversial – Lithuania and Ducal Prussia initially refused to recognise the Transylvanian as their ruler. Piotr Zborowski supported Bathory as he wanted to promote a princely or ducal candidate. He also endorsed the Duke of Ferrara. The wealthy port city of Gdańsk (Danzig) staged a revolt, and, with the help of Denmark, blockaded maritime trade to neutral Elbląg (Elbing). Báthory, unable to penetrate the city's extensive fortifications, succumbed to the demands for greater privileges and freedoms. However, his successful Livonian campaign ended in the annexation of Livonia and the Duchy of Courland and Semigallia (modern-day Estonia and Latvia, respectively), thus expanding the Commonwealth's influence into the Baltics. Most importantly, Poland gained the Hanseatic city of Riga on the Baltic Sea.

In 1587, Sigismund Vasa – the son of John III of Sweden and Catherine Jagiellon – won the election, but his claim was overtly contested by Maximilian III of Austria, who launched a military expedition to challenge the new king. His defeat in 1588 at the hands of Jan Zamoyski sealed Sigismund's right to the throne of Poland and Sweden. Sigismund's long reign marked an end to the Polish Golden Age and the beginning of the Silver Age. A devout Catholic, he hoped to restore absolutism and imposed Roman Catholicism during the height of the Counter-Reformation. His intolerance towards the Protestants in Sweden sparked a war of independence, which ended the Polish–Swedish union. As a consequence, he was deposed in Sweden by his uncle Charles IX Vasa. In Poland, the Zebrzydowski rebellion was brutally suppressed.

Sigismund III then initiated a policy of expansionism, and invaded Russia in 1609 when that country was plagued by a civil war known as the Time of Troubles. In July 1610, the outnumbered Polish force comprising winged hussars defeated the Russians at the Battle of Klushino, which enabled the Poles to take and occupy Moscow for the next two years. The disgraced Vasili IV of Russia was transported in a cage to Warsaw where he paid a tribute to Sigismund; Vasili was later murdered in captivity. The Commonwealth forces were eventually driven out on 4 November 1612 (celebrated as Unity Day in Russia). The war concluded with a truce that granted Poland–Lithuania extensive territories in the east and marked its largest territorial expansion. At least five million Russians died between 1598 and 1613, the result of continuous conflict, famine and Sigismund's invasion.

The Polish–Ottoman War (1620–21) forced Poland to withdraw from Moldavia in southeastern Europe, but Sigismund's victory over the Turks at Khotyn diminished the supremacy of the Sultanate and eventually led to the murder of Osman II. This secured the Turkish frontier for the duration of Sigismund's rule. In spite of the victories in the Polish–Swedish War (1626–1629), the exhausted Commonwealth army signed the Treaty of Altmark which ceded much of Livonia to Sweden under Gustavus Adolphus. At the same time, the country's powerful parliament was dominated by nobles (Pic. 2) who were reluctant to get involved in the Thirty Years' War; this neutrality spared the country from the ravages of a political-religious conflict that devastated most of contemporary Europe.

During this period, Poland was experiencing a cultural awakening and extensive developments in arts and architecture; the first Vasa king openly sponsored foreign painters, craftsmen, musicians and engineers, who settled in the Commonwealth at his request.

Sigismund's eldest son, Ladislaus succeeded him as Władysław IV in 1632 with no major opposition. A skilled tactician, he invested in artillery, modernised the army and fiercely defended the Commonwealth's eastern borders. Under the Treaty of Stuhmsdorf, he reclaimed regions of Livonia and the Baltics which were lost during the Polish-Swedish wars. Unlike his father who worshipped the Habsburgs, Władysław sought closer ties with France and married Marie Louise Gonzaga, daughter of Charles I Gonzaga, Duke of Mantua, in 1646.