False Dmitry I () (or Pseudo-Demetrius I) reigned as the Tsar of Russia from 10 June 1605 until his death on 17 May 1606 under the name of Dmitriy Ivanovich (). According to historian Chester S.L. Dunning, Dmitry was "the only Tsar ever raised to the throne by means of a military campaign and popular uprisings". He was the first, and most successful, of three "pretenders" () who claimed during the Time of Troubles to be the youngest son of Ivan the Terrible, tsarevich Dmitry Ivanovich, who supposedly escaped a 1591 assassination attempt when he was eight years old. It is generally believed that the real Dmitry of Uglich died in Uglich in 1591. False Dmitry claimed that his mother, Maria Nagaya, anticipated the assassination attempt ordered by Boris Godunov and helped him escape to a monastery in the Tsardom of Russia, and the assassins killed somebody else instead. He said he fled to the Polish–Lithuanian Commonwealth after he came to the attention of Boris Godunov, who ordered him seized. Many Polish nobles did not believe his story, but nonetheless supported him. With the support of the Polish–Lithuanian Commonwealth, False Dmitry invaded the Russian Empire in 1605, but the war ended with the sudden death of Boris Godunov. Disaffected Russian boyars staged a coup against the new tsar, Feodor II. False Dmitry entered Moscow on 21 July 1605, and was crowned tsar. Maria Nagaya accepted him as her son and "confirmed" his story. False Dmitry's reign was marked by his openness to Catholicism and allowing foreigners into Russia. This made him unpopular with the boyars, who staged a successful coup and killed him eleven months after he took the throne. His wife of 10 days, Marina, would later "accept" False Dmitry II as her fallen husband. Background Dmitry entered history circa 1600, after making a positive impression on Patriarch Job of Moscow with his learning and assurance. Tsar Boris Godunov ordered the young man seized and questioned. Dmitry fled to Prince Constantine Ostrogski at Ostroh, in the Polish–Lithuanian Commonwealth, and subsequently entered the service of the Wiśniowieckis, a polonized Ruthenian family. The princes Adam and Michał Wiśniowiecki in particular showed interest in the stories Dmitry told, and who he purported to be, as they gave the Poles an opportunity to capitalize on the political rancor in Moscow. Rumors said that Dmitry was an illegitimate son of the Polish king, Stefan