It was owing to Laski's intrigues that the new hospodar of Moldavia, Petrylo, after doing homage to the Porte, intervened in the struggle as the foe of both Ferdinand and Sigismund, and besieged the Grand Hetman of the Crown, Jan Tarnowski, in Obertyn, where, however, the Moldavians (August 22, 1531) sustained a crushing defeat, and Petrylo was slain.
Nevertheless, so anxious was Sigismund to avoid a collision with the Turks, that he forbade the victorious Tarnowski to cross the Moldavian frontier, and sent a letter of explanation to Constantinople.
Complications with the Turk were avoided by the adroit diplomacy of the king, while the superior discipline and efficiency of the Polish armies under the great Tarnowski (q.v.) and his pupils overawed the Tatars and extruded the Muscovites, neither of whom were so troublesome as they had been during the last reign.
Historical work has been produced by Hirschberg, Pappee, Sobieski, Czermak and others, and the histories of Polish literature by Stanislaus Tarnowski and Piotr Chmielowski are of the highest value, the former dealing more with the aesthetic side of literature and the latter with the historical.
Bruckner (Leipzig, 1901; also written in Polish); Chmielowski, History of Polish Literature (in Polish, 3 vols.); Stanislaus Tarnowski, History of Polish Literature (in Polish); Grabowski, Poezya Polska po roku 1863 (Cracow, 1903); Heinrich Nitschmann, Geschichte der polnischen Literatur (Leipzig; sine anno).
In foreign affairs Sigismund was largely guided by the Laskis (Adam, Jan and Hieronymus), Jan Tarnowski and others, most of whom he selected himself.