On 24 May, Hitler visited General von Rundstedt's headquarters at Charleville. The terrain around Dunkirk was thought unsuitable for armour. Von Rundstedt advised him the infantry should attack the British forces at Arras, where the British had proved capable of significant action, while Kleist's armour held the line west and south of Dunkirk to pounce on the Allied forces retreating before Army Group B. Hitler, who was familiar with Flanders' marshes from the First World War, agreed. This order allowed the Germans to consolidate their gains and prepare for a southward advance against the remaining French forces.