During a German counteroffensive in February 1943, the Czechoslovak battalion was ordered to defend the frozen river in the vicinity of Kharkov. Jaroš's strengthened 1st Company took position in front of the river in the village of Sokolovo; the rest of the battalion and supporting Soviet units stayed behind the river. On the afternoon of 8 March, German armored troops with at least 14 tanks launched two attacks on Sokolovo. In the ensuing battle, 1st Company was almost annihilated, and Jaroš was killed. Fighters of his company destroyed about 19 tanks and 6 APCs. They were ordered to remain until reinforcements could arrive, but the supporting tanks could not cross the thawing river (the battalion's commander had neglected to take into account the terrain). It wasn't until late that night that the remnants of 1st Company were ordered to retreat. Any further defense of Sokolovo had lost any value, as the unfrozen river no longer provided an avenue for the Germans to advance.