"It started on September 6 - the Germans were already converging on Warsaw - when small French patrols cautiously poked across the frontier in three places: along the Moselle River and the Luxembourg border; and in a salient southwest of Saarbrücken... For the next three weeks the French continued the piecemeal advance which was in accord with the strategic instructions of General Maurice Gamelin, Supreme Commander of the Allied forces, that the ruling factor should be not to sacrifice man power in rash attacks on fortified positions. With care and foresight the French reduced each individual pill-box and cleared the woods and fields of treacherous mines. By September 27 they had wormed forward only between 2 and 5 miles and nowhere did they threaten the West Wall. On that day Warsaw fell."
"Two days later Premiere Daladier conferred with General Gamelin and other French commanders. The result was a decision that France would give up the initiative on the Western Front that had failed to aid Poland and revert to a strictly defensive policy."