Progress was also made on both sides of the Oise, the French advancing within two miles of La Fère to the northern edge of the forest of St. Gobain, which forms the western defense of the Laon region. The Massif of St. Gobain formed the pivot of the German system, whose importance was only comparable to that of Cambrai for British operations. One great factor which aided materially in the advance of the Allies was the great increase in their engines of offense, whether in armored cars, tanks, Stokes guns, or great cannon, that could smash whole blocks of defense at one shot. The French were now supplied with howitzers of twenty-one inch caliber whose shell, over six feet long, could wreck a dozen batteries in a protected ravine, or wipe out an entire regiment hidden in an apparently impenetrable cave. So far the first part of Marshal Foch's program had been accomplished. The Germans had been driven back along the whole line from Arras to Rheims, and had practically lost all ground won in their four great drives which began on March 21, 1918, and ended on July 18, 1918, when Foch dealt a smashing blow on their flank between the Marne and the Aisne. During September 9-10, 1918, in spite of heavy rainstorms which halted Haig's men to provide shelters on recovered ground, the British advanced their line nearer Cambrai, fighting off strong German attacks in that region. Meanwhile the French gained three and a half miles, and occupied positions near St. Quentin on three sides. This new dash brought them nearer the flanking of La Fère on the north and south. September 12, 1918, was a memorable day in the history of the American Army in France when under command of General Pershing they launched an attack from all sides of the St. Mihiel salient that resulted in the capture of the town of that name and over 13,000 prisoners. The American army was now operating under its own command instead of fighting as part of a British or French army. All day and far into the night the fight was continuous on the British front, when the heights of Avrincourt were stormed and positions won that overlooked the German defenses for many miles. Further progress was made in the Havrincourt region during September 13-14, 1918, where to the southeast of Cambrai the British established posts east and north of the village of Havrincourt. General Pétain meanwhile had launched an attack on an eleven-mile front on both sides of the Ailette River between the Aisne and the Vesle, advancing his line to a distance of two miles at the farthest point and capturing over 1,000 prisoners. This French drive was of special importance, for it threatened to turn the flank of the German defensive positions on the Chemin-des-Dames, and weakened the enemy's hold on Laon. South of the Ailette the French won the famous Mont des Singes, and the villages of Allemant and Sanoy.