[2] Following the advice of his uncle, Colonel František Konopásek, Jaroš entered the military academy in Hranice.

With the rank of lieutenant since October 1941, Jaroš, together with other Czech officers, became a constituent member of the First Czechoslovak Independent Field Battalion in Buzuluk in 1942.

[1] During a German counteroffensive in February 1943, the Czechoslovak battalion was ordered to defend the frozen river in the vicinity of Kharkov.

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).

Any further defense of Sokolovo had lost any value, as the unfrozen river no longer provided an avenue for the Germans to advance.

For his heroism Otakar Jaroš was posthumously promoted to captain, and on 17 April 1943 he was decorated with the Gold Star of the Hero of the Soviet Union, the first member of a foreign army to be so honoured.

[4] Otakar Jaroš received a few decorations issued by the Soviet and Czech Communist parties.