Švitrigaila with several thousand troops (estimated to total about 40,000) marched out of Polotsk, where he was staying, and took Minsk, Kreva, Ašmena, and was preparing to attack Vilnius. Sigismund Kęstutaitis Lithuanian and Samogitian army supported by Masurians from Drahichyn (estimated to total about 20,000 people) attacked Švitrigaila's Lithuanian and Russian troops supported by Tatars, led by Khan Sayid Ahmad I. Švitrigaila's ally Livonian Order did not arrive it in time for the battle.