The French claimed that Articles 42 to 44 of the peace treaty of Versailles concerning the demilitarisation of the Rhineland had been broken.[2] These had designated a neutral zone 50 kilometres deep on the left bank of the Rhine. In this area any construction of fortifications or any military maneuvers were strictly forbidden, it being further specified that any breach would "be regarded as committing a hostile act against the Powers signatory of the present Treaty and as calculated to disturb the peace of the world." When the German Army sent 7,000 troops into the areas north of the River Lippe, the French government concluded that this was a breach of the treaty, and promptly responded by sending their own troops into the Neutral Zone.[3]:228