The idea of using the Reserve Army in the German homeland for a potential coup existed before, but apart from Hitler himself, only Colonel-General Friedrich Fromm, Chief of the Reserve Army since 1938, could initiate Operation Valkyrie. Fromm's refusal to co-operate in a prospective coup posed a serious obstacle to the conspirators. Nevertheless, after the lessons of a failed assassination attempt on 13 March 1943, Olbricht felt that the original coup plan was inadequate and that the Reserve Army should be used in the coup even without Fromm's co-operation.