 In early 1941 Stalin authorized the State Defense Plan 1941 ( DP @-@ 41 ) , which along with the Mobilization Plan 1941 ( MP @-@ 41 ) , called for the deployment of 186 divisions , as the first strategic echelon , in the four military districts of the western Soviet Union that faced the Axis territories ; and the deployment of another 51 divisions along the Dvina and Dnieper rivers as the second strategic echelon under Stavka control , which in the case of a German invasion was tasked to spearhead a Soviet counteroffensive along with the remaining forces of the first echelon . But on 22 June 1941 the first echelon only contained 171 divisions , numbering 2 @.@ 6 – 2 @.@ 9 million ; and the second strategic echelon contained 57 divisions that were still mobilizing , most of which were still seriously understrength . The second echelon was undetected by German intelligence until days after the invasion commenced , in most cases only when the German ground forces bumped into them . 
