Combating heresy and giving Poland a strong and stable government were the primary goals of Sigismund.
In the time of the Polish–Lithuanian Commonwealth, the Poles were a force to be reckoned with, especially their elite, heavy cavalry, most notably the Winged Hussars.
While the Russians were fighting among themselves in a civil war (Time of Troubles), Sigismund saw an opportunity to invade and take power, as did Sweden though they were never firmly on one side or the other.

The "Time of Troubles" was a dark period in Russia's history; it began when Tsar Feodor I died in 1598, which caused internal instability and a succession crisis upon the extinction of the Rurik dynasty.
Further setbacks that contributed to the escalation of violence was the famine of 1601 to 1603 which killed approximately 2 million Russians.
As the situation in Russia deteriorated, Sigismund enhanced Polish nobles and magnates to influence Russian boyars.
The new Tsar, Boris Godunov, proved to be an ineffective ruler and died after a lengthy illness and a stroke in April 1605.
He left one son, Feodor II, who succeeded him and ruled for only a few months, until he and Boris' widow were murdered by the enemies of the Godunovs in Moscow in June 1605.
Rumours circulated that they were murdered on the orders of king Sigismund but no real evidence of that exists.
Simultaneously, various pretenders to the Russian throne appeared claiming to be Tsarevich Dmitry Ivanovich, the youngest son of Ivan the Terrible.
In fact, the real Tsarevich died at the age of eight in 1591.
After the fall of impostor False Dmitry I and his Polish wife Marina Mniszech (known in Russian historiography as Marinka the Witch), Vasili Ivanovich Shuysky was crowned as Vasili IV of Russia.

The death of False Dmitry proved as an excuse for Sigismund to prepare an invasion.
Prior invasions and raids between 1605 and 1609 were conducted by Polish nobles with the help of hired Cossacks and foreign mercenaries.
Sigismund's primary intention was to destroy the Russian state in total and impose Catholicism under any condition, with the use of force if necessary.
Lew Sapieha, Grand Chancellor of Lithuania, who sought neutrality proposed to Boris Godunov an alliance or "eternal peace" treaty between Russia and Poland, but the idea did not gain wide support and was declined.

The Commonwealth army under the command of Hetman Stanisław Żółkiewski, who initially opposed to this conflict but could not disobey Sigismund's orders, crossed the border and on 29 September 1609 laid siege to Smolensk.
On 4 July 1610, at the Battle of Klushino, the outnumbered Polish force achieved a decisive victory over Russian troops, mostly due to the tactical competence and skill of Żółkiewski as well as the military prowess of Polish hussars.
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.
Seven Boyars proclaimed Polish prince Władysław, Sigismund's son, as the new Tsar of Russia.
In June 1611 Smolensk finally fell to the Poles.
Former Tsar Vasili Shuysky was transported in a wagon to Warsaw, where he paid tribute (Shuysky Tribute) to Sigismund and the Senate at the Royal Castle on 29 October 1611.
He eventually died in Gostynin as prisoner; he was most likely poisoned as his brother died soon after.
The Polish army also committed numerous atrocities while stationing in Moscow.

In 1611, Kuzma Minin and Prince Dmitry Pozharsky formed a new army to launch an uprising against the Polish occupation.
Sigismund's forces withdrew from ruined Moscow in September 1612.
News of the capitulation reached Sigismund on December 8 at Volokolamsk.
The war continued with little military action until 1618 when the Truce of Deulino was signed, which granted Poland new territories, including the city of Smolensk.
The agreement marked the greatest geographical expansion of the Polish–Lithuanian Commonwealth (0,99 million km²) until the loss of Livonia in 1629.
However, Russia was able to ret
Combating heresy and giving Poland a strong and stable government were the primary goals of Sigismund. In the time of the Polish–Lithuanian Commonwealth, the Poles were a force to be reckoned with, especially their elite, heavy cavalry, most notably the Winged Hussars. While the Russians were fighting among themselves in a civil war (Time of Troubles), Sigismund saw an opportunity to invade and take power, as did Sweden though they were never firmly on one side or the other.
The "Time of Troubles" was a dark period in Russia's history; it began when Tsar Feodor I died in 1598, which caused internal instability and a succession crisis upon the extinction of the Rurik dynasty. Further setbacks that contributed to the escalation of violence was the famine of 1601 to 1603 which killed approximately 2 million Russians. As the situation in Russia deteriorated, Sigismund enhanced Polish nobles and magnates to influence Russian boyars. The new Tsar, Boris Godunov, proved to be an ineffective ruler and died after a lengthy illness and a stroke in April 1605. He left one son, Feodor II, who succeeded him and ruled for only a few months, until he and Boris' widow were murdered by the enemies of the Godunovs in Moscow in June 1605. Rumours circulated that they were murdered on the orders of king Sigismund but no real evidence of that exists. Simultaneously, various pretenders to the Russian throne appeared claiming to be Tsarevich Dmitry Ivanovich, the youngest son of Ivan the Terrible. In fact, the real Tsarevich died at the age of eight in 1591. After the fall of impostor False Dmitry I and his Polish wife Marina Mniszech (known in Russian historiography as Marinka the Witch), Vasili Ivanovich Shuysky was crowned as Vasili IV of Russia.
The death of False Dmitry proved as an excuse for Sigismund to prepare an invasion. Prior invasions and raids between 1605 and 1609 were conducted by Polish nobles with the help of hired Cossacks and foreign mercenaries. Sigismund's primary intention was to destroy the Russian state in total and impose Catholicism under any condition, with the use of force if necessary. Lew Sapieha, Grand Chancellor of Lithuania, who sought neutrality proposed to Boris Godunov an alliance or "eternal peace" treaty between Russia and Poland, but the idea did not gain wide support and was declined.
The Commonwealth army under the command of Hetman Stanisław Żółkiewski, who initially opposed to this conflict but could not disobey Sigismund's orders, crossed the border and on 29 September 1609 laid siege to Smolensk. On 4 July 1610, at the Battle of Klushino, the outnumbered Polish force achieved a decisive victory over Russian troops, mostly due to the tactical competence and skill of Żółkiewski as well as the military prowess of Polish hussars. 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. Seven Boyars proclaimed Polish prince Władysław, Sigismund's son, as the new Tsar of Russia. In June 1611 Smolensk finally fell to the Poles. Former Tsar Vasili Shuysky was transported in a wagon to Warsaw, where he paid tribute (Shuysky Tribute) to Sigismund and the Senate at the Royal Castle on 29 October 1611. He eventually died in Gostynin as prisoner; he was most likely poisoned as his brother died soon after. The Polish army also committed numerous atrocities while stationing in Moscow.
In 1611, Kuzma Minin and Prince Dmitry Pozharsky formed a new army to launch an uprising against the Polish occupation. Sigismund's forces withdrew from ruined Moscow in September 1612. News of the capitulation reached Sigismund on December 8 at Volokolamsk. The war continued with little military action until 1618 when the Truce of Deulino was signed, which granted Poland new territories, including the city of Smolensk. The agreement marked the greatest geographical expansion of the Polish–Lithuanian Commonwealth (0,99 million km²) until the loss of Livonia in 1629. However, Russia was able to ret
Sigismund III Vasa