In 1942 Buršík joined the Soviet organized First Czechoslovak Independent Field Battalion, under the command of Ludvík Svoboda. He started with a rank of corporal and was promoted to Warrant Officer. The battalion first saw combat in the Battle of Sokolovo in March 1943, and Buršík was wounded during the fighting. During the Battle of Kiev Buršík was one of the first to make it to the center of the city, for which he was awarded the Gold Star of the Hero of the Soviet Union in December 1943. The Czechoslovak battalion continued fighting on the Eastern Front until the end of the war. Buršík finished the war with the rank of captain.