[12][13] Catherine ensured that her son was educated in the spirit of Catholicism and Polish patriotism; the young prince was made aware of his blood connection to the Jagiellonian dynasty which ruled Poland in its finest period for two hundred years.

[2] His candidacy was secured by Queen Dowager Anna and several elite magnates who considered him a native candidate as a descendant of the Jagiellons, though the election was openly questioned and opposed by the nobles politically associated with the Zborowski family.

[22] When the news reached Sigismund in Sweden, he crossed the Baltic and landed in Poland on 7 October, immediately agreeing to grant royal privileges to the Sejm (parliament) in the hope of calming the opposition and settling the disputed election.

[29] Sigismund was crowned at Uppsala on 19 February 1594,[30] but his promise to uphold the Protestant faith in Sweden began on shaky ground, as demonstrated by the presence of a papal nuncio in the royal procession.

[38] During the first parliament sitting, the so-called Pacification Sejm, in March 1589, Zamoyski proposed extensive reforms of the electoral system; notably, he presented the idea that only a member of a local native dynasty should be eligible to the Polish throne in the future, entailing the permanent exclusion of any Habsburg candidates.

[40] At the subsequent Sejm session, assembled in March 1590, Zamoyski persuaded the gathered deputies and representatives to exclude Archduke Maximilian from future candidacy to the throne, describing the possibility of Austrian intrigues and the looming threat of the Turkish Empire.

[24] Sigismund's leniency towards the Habsburgs also alienated some clerics; the Austrians wanted to prevent Andrew Báthory from seizing the bishopric of Kraków and succeeded in doing so by diplomatic coaxing or coercion.

[44] The new papal nuncio, Annibale di Capua, a staunch Habsburg supporter, eventually convinced Sigismund to nominate Jerzy Radziwiłł after Piotr Myszkowski died on 5 April 1591.

[47] As outlined by Oskar Halecki, the king's friends were largely recruited from the higher clergy and the Jesuits, who violated the 1573 Warsaw Confederation guaranteeing religious freedoms in Poland and Lithuania.

[48] Zamoyski joined the dissidents, and, when Sigismund failed to prevent mob violence directed against non-Catholics in Vilnius and Kraków in 1591, he summoned several conventions that "demanded the guarantees of security".

[56] Niemcewicz largely attributed the victory to Sigismund – the measures of the Counter-Reformation strengthened[57] and within a year many of the convention's attendees died; acquiescent nobles favourable to the king were appointed as their successors, thus making his position less vulnerable.

[58][59] The Uppsala Resolution of 1594 dictated the rights and securities of Protestants in Sweden; it promised to uphold the Lutheran faith in the country, forbade non-Lutherans from being appointed to office or participating in the educational system and prevented Sigismund from freely raising taxes for war.

[66] After the fall of Kalmar, Charles found himself with major trouble on his hands; the Polish Crown army attracted Swedish followers, and Stockholm, lacking military defence, was easily taken with the help of the nobility and officers of Götaland.

The prevailing fog was instrumental at hiding troop movement; the Swedish rebels used the opportunity to take the bridges on the river Stångån when Sigismund's men were falsely led into a truce and retreated to their camp.

[71] He was given six[69] (or twelve depending on source)[71] months to send his son, Prince Ladislaus (Władysław) Vasa, to Sweden as his successor, under the condition that the boy would be brought up in the Protestant faith.

"[76] He presented his credentials, kissed the Queen's hand, then walked to the centre of the chamber and, as outlined by Cecil, "began his oration aloud in Latin, with such a gallant countenance as in my life I never beheld.

[90] Despite the failure to overthrow Sigismund, the rebellion firmly established the rights and privileges of nobles in the Polish political system, confirmed the inviolability of the royal elections and religious tolerance.

[99] Lew Sapieha, Grand Chancellor of Lithuania, sought neutrality by proposing to Boris Godunov an "eternal" peace treaty between Russia and Poland–Lithuania, but the idea did not gain support and was declined.

[103] The battle was a major blow to the Russians; Tsar Vasili IV was subsequently ousted by the Seven Boyars and Żółkiewski entered Moscow beginning the two-year tyrannical occupation of the Kremlin.

[105] In June 1611 Smolensk fell to the Poles;[105] the deposed Vasili Shuysky was transported in a caged wagon[106] to Warsaw, where he paid tribute to Sigismund and the Senate at the Royal Castle on 29 October 1611.

[114] British historian Robert Nisbet Bain wrote that his plan was to invade and possibly occupy Transylvania, then an Ottoman ally and therefore considered dangerous to the Habsburg monarchy and Poland.

[123] The Treaty of Khotyn was signed on 9 October 1621 which resulted in no territorial gain or loss, but Sigismund was to relinquish his claims on Moldavia and the Ottoman Empire was prevented from marching into Poland.

[125] Following a series of conflicts between Poland and Sweden in 1600–1611, 1617–1618, and 1621–1625, all of which ended in a stalemate, Gustavus Adolphus invaded in 1626 to gain control over Livonia and relinquish Sigismund's claim to the Swedish crown.

[135] As the major trade ports on the coast of the Baltic Sea were blocked by Swedish vessels, Sigismund sent a small squadron of ten ships under Arend Dickmann to engage the Swedes at the Battle of Oliva.

[145] His hate towards Evangelicals coupled with the advice of Jesuit priests led to repressions and the eventual demise of the Polish Brethren decades later; their expulsion from Poland in 1658 contributed to the spread of Unitarianism across the globe.

[150] However, trade practices continued to thrive and Poland remained a safe haven for refugees fleeing oppression in other parts of the continent, chiefly during the Thirty Years' War.

[181][182] Sigismund and his sons left a collection of tangible memorabilia, including commemorative coins (numismatics), reliquaries, silverware, tableware, jewellery and precious personal belongings marked with royal monograms or crests.

[185] Upon the marriage to his first wife, Anne of Austria, on 25 November 1592 he ordered a themed masquerade on Kraków's Main Market Square and, to the disbelief of his subjects, danced for the public.

[186] Sigismund was also known to be physically active in his youth[187] and enjoyed occasional hunting, ice skating and frequently played football; he is widely credited for introducing and popularising the sport in Poland.

Certain leading magnates were initially opposed to the marriage,[198] however the opinion shifted in her favour due to personal characteristics; she was known to be attentive, sharp-minded, humble, pious and kind, though of poor health.