The Commonwealth army under the command of Hetman Stanisław Żółkiewski 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 of the Polish winged 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. The Seven Boyars proclaimed Polish prince Ladislaus, Sigismund's son, as the new Tsar of Russia. In June 1611 Smolensk fell to the Poles; the deposed Vasili Shuysky was transported in a caged wagon to Warsaw, where he paid tribute to Sigismund and the Senate at the Royal Castle on 29 October 1611. He eventually died in captivity at Gostynin; he was most likely poisoned as his brother died soon after. The Polish army also committed countless atrocities while stationing in Moscow.