On March 7, 1936, German troops marched into the demilitarized zone in the Rhineland. Hitler justified his action by charging that the Franco-Russian Treaty was a direct contradiction to the Locarno Treaty; thus Germany was not bound by the former. France responded with a troop concentration on their border. On the same day, Hitler stated that he was now willing to return to the League of Nations, and wanted to begin negotiations immediately with France and Belgium over the status of the Rhineland. In addition, he offered 25-year non-aggression pact to France and Belgium.

France and Belgium brought the issue to the League Council, and on March 14th Germany was condemned for violating the Lacarno Treaty. Britain acted as a mediator while professing continued support for the Locarno Treaty. No progress had been made by April 21st when the Germans began constructing fortifications in the demilitarized zone. Little change occurred in the status of the disputed area during the summer of 1936. No action was taken Germany despite several meetings of the remaining Locarno powers. The following October, Belgium declared its neutrality and stated that collective security had collapsed. Several proposals were made and conferences held, but the reality of German occupation of the the Rhineland was accepted by all Europe.