The Battle of the Marne by G.H. Perris — Read

On the Ourcq, each adversary was bringing up reserves, and was trying to turn the other by the north, with a slight advantage in time on the French, but a superiority of speed on the German, side. We left the centre of the 6th Army, on September 6, practically stationary about Marcilly and Barcy; while, moving from Brégy and Bouillancy, the 7th Corps gained Puisieux and Acy during the afternoon, and the 8th Division, thrown across the Marne, drove some enemy contingents into the woods of the river loop east of Meaux. Maunoury decided to attack frontally the three plateaux of Vareddes, Trocy-Vincy, and Etavigny, throwing picked columns into the valleys between, that of the Therouanne at Etrepilly and the Gergoyne ravine at Acy-en-Multien, in the hope of turning the hill positions. His field batteries were now in force at Bouillancy, Fosse-Martin, La Ramée, Marcilly, and Penchard; but he had no heavy artillery.

Worse, from September 5, when his only aviator was brought down at Vareddes, to September 9, when Captain Pellegrin found a machine and discovered the nest of German mortars in the gullies by Trocy, he had no air scouts, so that, almost throughout the battle, the German gunners dominated the field.