The De la Gardie campaign was a joint military campaign by the Tsardom of Russia and Sweden during the Polish–Muscovite War from April 1609 to June 1610. Russia was unofficially occupied during the early Time of Troubles by the Polish–Lithuanian Commonwealth, which had supported False Dmitry II as the Tsar of Russia since 1607. Tsar Vasili IV formed a military alliance with Sweden in 1609, providing a 5,000-strong auxiliary corps commanded by Jacob De la Gardie and Evert Horn to support Russian forces under Mikhail Skopin-Shuisky. The De la Gardie campaign was successful against False Dmitry II, dispersing his court in Tushino – a former village and town to the north of Moscow, but failed against the Polish–Lithuanians and was defeated at the Battle of Klushino on 4 June 1610. Prelude The Tsardom of Russia had been experiencing the Time of Troubles (1598–1613) since the death of Tsar Feodor I in 1598, causing widespread political instability and a violent succession crisis for the title of Tsar of Russia by usurpers known as the False Dmitris. In 1605, the Polish-Muscovite War started when the Polish–Lithuanian Commonwealth unofficially invaded Russia in support of False Dmitry I against the unpopular crowned tsar Boris Godunov, seeking to exploit the country's weakness for their own gain. Godunov died in June 1605 and was replaced by False Dmitry I, whose popularity among the Russian populace declined rapidly during his reign, and the Polish withdrew when he was eventually murdered during an uprising in Moscow in May 1606. Despite this, Russia's instability continued to the near-total breakdown of order, prompting the Polish to invade again in 1607 in support of the new usurper, False Dmitry II. In 1609, the Tsar of Russia at the time, Vasili IV, approached King Charles IX of Sweden to form a military alliance against False Dmitry II and the Polish occupiers. The two signed the Treaty of Viborg (Vyborg; Finnish: Viipuri), in which Russia ceded Kexholm County and the strategic Korela Fortress to Sweden in exchange for military support. This Russian alliance formed in 1609 with Sweden, the main rival of Poland, led to King Sigismund III of Poland officially declaring war on Russia in response. Campaign against False Dmitry II In 1608–1613, De la Gardie as Sweden's Chief Commander in Finland also commanded the Swedish war efforts in Russia. Thus, in accordance with the Swedish-Russian military alliance formed in 1609, he