In 1600 Zamoyski and hetman Jan Karol Chodkiewicz gathered Commonwealth forces, returning to Moldavia, where they fought Mihai. Zamoyski defeated Mihai Viteazul near Bucov (Bukova) in Wallachia, on the Teleajen river, near present-day Ploiești, restored Ieremia Movilă to the throne, and helped his brother Simion Movilă to gain the throne in Bucharest, thus temporarily extending the sphere of Commonwealth influence south all the way to the Danube. In the meantime, Mihai Viteazul traveled to Vienna to ask for the Emperor's help, in exchange for assisting the Habsburgs against the Ottomans and Imperial influence over Moldavia, previously aligned with the Commonwealth. The Emperor promised help and in 1601 sent an army led by Giorgio Basta that was to accompany Mihai on the way back. Upon their arrival in Transylvania, after the joint victory at Gurăslău against the prince of Transylvania, Sigismund Báthory, general Basta assassinated Mihai Viteazul during the night, on the field of Câmpia Turzii (south of Cluj), effectively taking Transylvania under the Emperor's lead.