During World War II, Fall Rot (Case Red in English) was the second phase of the conquest of France by the German Army, begun on 5 June 1940. It had been made possible by the success of Operation Fall Gelb in the Battle of France. Before the invasion, it had not yet been decided whether mainland France would be attacked; this would depend on the outcome of Fall Gelb. Fall Rot consisted of two suboperations: first a preliminary attack was carried out in the west over the river Somme in the direction of the Seine; the main offensive started on 9 June in the centre over the river Aisne. It broke the French front and allowed German armour to cut off the armies in the Maginot Line on 17 June. That same day France asked for an armistice, officially capitulating on 25 June.