The Battle of Oshmyany took place on 8 December 1432 at Oshmyany (present Ashmyany, Hrodna Voblasts, Belarus) between the two contenders for the throne of the Grand Duchy of Lithuania grandchildren of Gediminas: Švitrigaila (on the maternal line the grandson of Aleksandr of Tver, executed in the Golden Horde in 1339) and Sigismund Kęstutaitis led troops of Oshmyany supporters. Švitrigaila led Lithuanians, Rusins and Tatars, and even help from the Grand principality of Tver, and Sigismund his supporters and detachments from Poland. Polish chroniclers attribute a numerical advantage to Švitrigaila's army, but it was unlikely to be significant, if at all. On both sides came together thousands of twenty soldiers. For that period, those were quite impressive forces. Švitrigaila first squeezed the rows of Sigismund's army, and the victory sloped in his direction, but his cousin was able to reverse the course of the battle (obviously thanks to Polish troops) and win. The battle lasted the entire light day until nightfall. Polish chroniclers talk about tens of thousands of dead and four thousand captive Ruthenians, but this is probably an exaggeration of the winners. Really, of course the Švitrigaila army suffered quite significant losses, but the army of its rival and cousin was also greatly weakened.
Švitrigaila was forced to retreat to Polotsk. Prisoners of Sigismund were captured by his commanders - Jurgis Gedgaudas (c1370-1435), Yuri Lugvenovich of Mstislavl (c1396-1460), and princes of Drutsk Fyodor Odintsovich, Dmitri Semyonovich Sokira Zubrevitsky Slutsky and Vasili Semyonovich Krasnyi.