Nachtigall Battalion
Most battalions were assigned block numbers based on ethnic and national makeup for ease of recognition. Those in Russia South and the heart of Ukraine were numbered from 101 to 200. The ones operating in Russia Center and in Byelorussia were numbered from 51 to 100. An exception was Battalion 201, which was formed not in Galicia but in Frankfurt an der Oder in October 1941, from members of the disbanded Nachtigall Battalion, formed originally by OUN-B.