 In December 1917 he switched to Ukrainian service where his first assignment was the 2nd Serdyuk Division which was only starting to form and at that time consisted out a small officer corps.One of the Hrekov's first remarkable subordinates on the side of the Ukrainian People's Army was a colonel Petro Bolbochan.At one time the Russian prime-minister Vladimir Lenin was offering 50,000 rubles in silver for the head of colonel Bolbochan.