Behind Versailles and St. Germain, the Forest of Marly is literally enclosed by batteries outlying the extreme strong works of “Le Trou de Fer.” Behind this group stands the high and prominent fort of Mont Valérien, which still maintains great military value for defence. While Paris was waiting for the approach of the enemy, he altered his plans and made an unexpected move. As Sir John French said in his despatch of September 15:— On Friday, September 4, it became apparent that there was an alteration in the direction of advance of almost the whole of the First Germany Army. That army, since the battle near Mons, on August 23, had been playing its part in the colossal strategic endeavour to create a Sedan for the Allies by outflanking and enveloping the left of their whole line, so as to encircle and drive both British and French to the south. There was now a change in its objective; and it was observed that the German forces opposite the British were beginning to move in a south-easterly direction, instead of continuing south-west on the capital. Leaving a strong rearguard along the line of the River Ourcq (which flows south, and joins the Marne at Lizy-sur-Ourcq) to keep off the French 6th Army, which by then had been formed, and was to the north-west of Paris, they were evidently executing what amounted to a flank march diagonally across our front. Prepared to ignore the British, as being driven out of the fight, they were initiating an effort to attack the left flank of the French main army, which stretched in a long curved line from our right towards the east, and so to carry out against it alone the envelopment which had so far failed against the combined forces of the Allies. On Saturday, the 5th, this movement on the part of the Germans was continued, and large advanced parties crossed the Marne, southwards at Trilport, Sammeroy, La Ferté-sous-Jouarre, and Château Thierry. There was considerable fighting with the French 5th Army on the French left, which fell back from its position south of the Marne towards the Seine. On Sunday, the 6th, large hostile forces crossed the Marne and pushed on through Coulommiers past the British right. Farther east they were attacked at night by the French 5th Army, which captured three villages at the point of the bayonet. On Monday, the 7th, there was a general advance on the part of the Allies in this quarter of the field. Our forces, which had by now been reinforced, pushed on in a north-easterly direction, in co-operation with an advance of the French 5th Army to the north and of the French 6th Army eastwards, against the German rearguard along the Ourcq.