In June 1936, under the leadership of Leon Blum, a Leftist Popular Front coalition of Socialists, Radical Socialists, and Communists assumed direction of the Third French Republic. A problem which quickly became apparent involved its relations with the Soviet Union. A mutual assistance pact between the two countries, lacking teeth due to French reluctance to conclude a military convention, had become something of a dead letter since its signing by the Rightist Laval Government in May 1935. The Soviets eagerly desired to transform the pact into an effective military alliance, and, indeed, relations between the two countries during the first year of the Popular Front centered around Soviet attempts to initiate negotiations for a supplementary military agreement. Given the Soviet concern, the increasingly aggressive nature of the Nazi threat, and the vigorous support for the Franco-Soviet Pact by the French Left prior to 1936, one might justifiably assume that the Popular Front would take the lead in promoting military cooperation. It did not. Instead, it must share a large portion of the responsibility for France's failure to conclude an effective military agreement with the Soviet Union, and this must be regarded as a weighty consideration in the latter's decision to pursue the path which ultimately led to the Nazi-Soviet Pact of August 1939. This, in turn, was of inestimable importance in the final collapse of the Third Republic; for -nothing can obscure the fact that the lack of an eastern front was a major factor in the debacle of 1940.