The French First and Second Armies attacked into Alsace-Lorraine on 19 and 20 August and were beaten back with severe loss by German forces, which were preparing for a counteroffensive. Joffre believed (20 August) that Liège was still holding out (in fact the last of the Liège forts had fallen on 16 August), and hoped that Lanrezac would be able to reach Namur, which was expected to hold out for even longer. The Germans entered Brussels that day, but Joffre was convinced, after the defeat in Alsace-Lorraine and air and cavalry reports of strong German forces in Belgium, that the German centre in the Ardennes must be weak. On 21 August the French Second Army was pressed by a German counterattack. Édouard de Castelnau asked for permission to abandon Nancy and its fortified heights, but Joffre forbade him to do so.