The conspiracy which attempted the coup on July 20, 1944 made various attempts to inform the Western Allies of their existence and get assurances that, if they succeeded in removing Hitler and establishing an interim government, the Western Allies would negotiate with them.  The first such attempt was made in the lead-up to the Sudeten Crisis in 1938.  Via the Vatican, the British government was informed about the possibility of a coup to prevent Hitler from invading the Sudetenland. However, the British government was not interested in aiding German generals against Hitler, and at that time even preferred Hitler to a government run, even temporarily, by the German General Staff.  It was a tragic misjudgment.

In the lull between the invasion of Poland and the start of the offensive in the West, one member of the Resistance, Hans Oster, warned the Dutch of the impending violation of Dutch neutrality—a move that has made him very controversial in Germany to this day.  But the Dutch didn't take the warnings seriously and were caught off guard despite the warning.

Later, the Allies were far too committed to Stalin to think of seriously negotiating with a post-Hitler government.  In consequence, they responded to all overtures with non-committal answers.  Some members of the conspiracy hoped nevertheless that once they had killed Hitler and seized power —i.e. had proved their effectiveness and presented the Allies with a concrete opportunity to stop the loss of life in the West— they might be able to effect at least a ceasefire in the West. Some of the conspirators were willing to open the Western Front to the Anglo-Americans and invite them into Berlin while holding the Russian Front.