Anglo French Supreme War Council, Where it was Decided to Halt Saar Offensive
On September 12, the Anglo French Supreme War Council gathered for the first time at Abbeville in France.
It was decided that all offensive actions were to be halted immediately. Maurice Gamelin ordered his troops to stop "not closer than 1 kilometre" from the German positions along the Siegfried Line. Poland was not notified of this decision. Instead, Gamelin informed marshal Edward Rydz-Śmigły that half of his divisions were in contact with the enemy, and that French advances had forced the Wehrmacht to withdraw at least six divisions from Poland. The following day the commander of the French Military Mission to Poland General Louis Faury informed the Polish chief of staff, general Wacław Stachiewicz, that the planned major offensive on the western front had to be postponed from September 17 to September 20. At the same time, French divisions were ordered to retreat to their barracks along the Maginot Line. The Phoney War had begun.
Supreme War Council, the Anglo-French co-ordinating committee which oversaw Anglo-French strategy before and during the fall of France in June 1940, but which had no operational powers. It first met at Abbeville on 12 September 1939. The last meeting took place near Tours on 13 June 1940 when British representatives included Churchill, Dill, and Beaverbrook, and French representatives included Reynaud, Pétain, and de Gaulle who had just been made under-secretary for National Defence.
BBC Online: World War II