[20] The opinion on this point of the officers who took part in the Battle of the Aisne is embodied in the following official note published by the British Press Bureau:-- "There is no doubt that the position on the Aisne was not hastily selected by the German Staff after the retreat had begun. From the choice of ground and the care with which the fields of fire have been arranged to cover all possible avenues of approach, and from the amount of work already carried out, it is clear that the contingency of having to act on the defensive was not overlooked when the details of the strategically offensive campaign were arranged." [21] The late General Hamley, describing what he considered the most effective lines for an invasion of France from Germany in opposition to the defensive adopted by Napoleon, points out that if the left of the defence threatens the invaders' communications, the invaders, leaving their right on the Ourcq and Marne, march through Sezanne to fight on the right bank of the Seine. Pushing the French right and centre to the Yères with their own centre and left, they fight then the decisive battle. It should be decisive, for the [Germans] on the two rivers, approaching each other in the narrowing angle can combine in a movement on Paris, holding the passages at Melun and Montereau on the one side, and at Meaux on the other. "In executing such a plan the weapons of the defender would be in some measure turned against himself.... But the assailants in taking these forward steps do so at the disadvantage of attacking a strongly posted enemy and under penalty of exposing a flank to him. This course demands a superiority in numbers of not less than 4 to 3, and probably greater than that." The Germans had adopted this very plan, but they had not the superiority they imagined. CHAPTER VII THE OPERATIONS ON THE AISNE The battle of the Aisne, destined to develop into the longest conflict on record--it extended over two whole months--began on the afternoon of Sunday, September 13. To follow its complexities it is necessary clearly to grasp, not only the military purposes or objectives the two sides had immediately in view, but the respective situations of the opposing masses as regards fighting efficiency. When operations are on this gigantic scale a certain amount of imagination must be exercised to realise even the barest facts. From Compiègne eastward to Rheims the Allied line was formed by the 6th French, the British, and the 5th French armies. To the first for the moment was assigned the duty of forcing the passages of the Aisne from below Soissons, clearing the enemy off the western end of the ridge, and pushing him up to Noyon on the Oise. The business which fell to the British army was that of delivering a frontal attack on this natural hill fortress from Soissons as far as Craonne.