The French have resumed offensive operations in the Champagne sector of the Western Front. They are not meeting much success and are suffering heavy casualties from German machine gun and artillery fire.
Fighting on the Western Front is far less mobile than in the east. The generals still dream of wars of movement and manoeuvre, but their soldiers are unable to make the kind of sweeping advances that are still possible in Poland. On the Eastern Front, the density of men and guns is far lower than in the west, making it easier for attacking armies to make gains by concentrating on a weakly defended sector. Each of the opposing armies is so concentrated on the Western Front that there are no sectors so weakly defended. Any attempt to advance must take place against relatively high concentrations of men and guns, ensuring that any such advance will be bloody and difficult. And even if an attacking force achieves a local superiority in numbers, the better transport infrastructure of Western Europe means that the enemy can quickly bring in reinforcements.
French machine gunners (The Great War blog)