Though the besieged had not hitherto succeeded in forcing their way through the enemy's lines, they now set about widening their elbow room, with intent that by their counter-approaches the ring of investment should be further and yet further pushed back, until at last it should reach the breaking point. On the south side the French entrenchments already extended beyond Vitry and Villejuif to the Seine; and on the north, between Drancy and Fort de l'Est, there was an extensive system of trenches and batteries reaching to within 1100 yards of Le Bourget, which in part might in a manner be dignified with the title of a regular engineer-attack. The hard frost had indeed hindered the further progress of these works, but they were armed with artillery and occupied by the IInd Army. And further, a singularly favourable point of support for a sortie to the east as well as to the north, was afforded to the French in the commanding eminence of Mont Avron, which, armed with seventy heavy guns, projected into the Marne valley like a wedge between the northern and southern investing lines.
(BOMBARDMENT OF MONT AVRON, DECEMBER 27TH.)--In order to expel the French from this position fifty heavy guns from Germany, and twenty-six from before La Fère were brought up under the command of Colonel Bartsch. By the exertions of a whole battalion as a working party, two groups of battery emplacements were erected in spite of the severe frost on the western slope of the heights behind Raincy and Gagny, and on the left upland of the Marne Valley near Noisy le Grand, thus encompassing Mont Avron on two sides at a distance of from 2160 to 3250 feet.
At half-past eight on the morning of 27th December those seventy-six guns opened fire. A heavy snowstorm interfered with accurate aim, and prevented any observation of the execution done. Mont Avron and Forts Nogent and Rosny replied rapidly and heavily.
The German batteries lost two officers and twenty-five gunners, several gun-carriages broke down under their own fire, and everything pointed to the prospect that no definite result would be obtained on that day.
But the batteries had fired more effectually than had been supposed. The clear weather of the 28th allowed of greater precision; the Prussian fire proved most telling, making fearful havoc in the numerous and exposed French infantry garrison. Mont Avron was silenced, and only the forts kept up a feeble fire. General Trochu, who was present in person, ordered the abandonment of the position, which was so effectually accomplished in the night by the energetic commander, Colonel Stoffel, that only one disabled gun was left behind.