The Fire of Moscow occurred when the Crimean and Ottoman Turkish army (8,000 Crimean Tatars, 33,000 irregular Turks and 7,000 janissaries) led by the khan of Crimea Devlet I Giray, bypassed the Serpukhov defensive fortifications on the Oka River, crossed the Ugra River, and rounded the flank of the 6,000-man Russian army. The sentry troops of Russians were crushed by the Crimean-Turkish forces. Not having forces to stop the invasion, the Russian army retreated to Moscow. The rural Russian population also fled to the capital. After defeating the Russian army, the Crimean-Turkish forces besieged the town Moscow, because in 1556 and 1558 Muscovy, violating the oath given to the Giray dynasty, attacked the lands of the Crimean Khanate — Moscow troops invaded the Crimea and burned villages and towns in the Western and Eastern Crimea, with many Crimean Tatars captured or killed. The Crimean Tatar and Ottoman forces set the suburbs on fire on 24 May and a sudden wind blew the flames into Moscow and the city went up in a conflagration. According to Heinrich von Staden, a German in the service of Ivan the Terrible (he claimed to be a member of the Oprichnina)," the city, the palace, the Oprichnina palace, and the suburbs burned down completely in six hours.