This was the final engagement in a struggle between the rival grand dukes Svidrigiello and Zygimantas Kenstutis for control of Lithuania. Svidrigiello’s army probably numbered about 30,000 men in all, composed of a cosmopolitan collection of Lithuanians, Hussite mercenaries, Russians from Kiev, Smolensk and Polotsk, Tartars, and Livonian Teutonic Knights (including their feudal vassals and Estonian and Latvian militia) under their Landmeister Franke Kersdorf. Its field-commander was probably Zygimantas Kaributas — the same as had once fought for the Hussites — since neither Svidrigiello nor Kersdorf would surrender command of their own forces to the other. Zygimanats Kenstutis’ army, of much the same size, similarly represented a coalition of forces, but this time only of Lithuanians and Poles, the latter comprising either 800 or 8,000 cavalry under his son Michael and Jacob Kobylany. Both sides fielded artillery.
The opposing forces faced each other across the Swienta River for 2 days before signs of withdrawal by Svidrigiello encouraged Kenstutis to attack. A Polish contemporary described Kaributas’ Hussite-inspired battle-formation as being drawn up ‘in the manner of the Bohemian heretics with a wall of wagons. The
Tartars were posted on one wing [while] the crusaders and the Livonian master were on the other wing’ in what he describes as ‘a scattered formation’, doubtless as a result of the attempted retreat that had encouraged Kenstutis’ attack. Beyond them, we are told, lay Svidrigiello and his ‘innumerable multitude of schismatics’ (i. e., the Russians).
Kenstutis sent his Lithuanians against the latter, while the Poles tackled the Tartars, the wagons and the Germans. In the face of their onslaught the Tartars performed their usual feigned flight, but made the mistake of withdrawing inside the Hussite wagon-fortress, where not only did they present a wonderful massed target to the Polish artillery, but also hampered Kaributas’ gunners as they tried to return their fire. The Poles then cut through Kersdorfs disordered troops and fell on the wagon-fortress, ‘a bigger fortification than any ever seen in Bohemia, and strongly bound together’; they broke into it and completely overwhelmed the Tartars and Hussites in the cramped space within.
Svidrigiello and his ‘schismatics’ had in the meantime fled before Kenstutis’ Lithuanians, but were closely pursued and likewise suffered heavy losses, including 13 princes killed and 12 captured. Among others killed in the battle were Kersdorf and 7 of his commanders, another source reporting that ‘almost all the Livonian knights perished’ (perhaps some 400, since that is the number of reinforcements subsequently requested from Prussia by the Livonian marshal). Zygimantas Kaributas was captured but, mortally wounded, died soon after.