To the south of the Avre River the French, as they fought their way forward, captured over 400 Germans, overcoming some important enemy strongholds.
From the positions captured by the French north of the Aisne River the Allies could now dominate the German batteries of big guns at Chavigny and Juvigny, north of Soissons. These batteries were formidable, commanding not only the city of Soissons, but a wide region around. The Allies were now able to exert such pressure on the Germans here that they must soon be forced to retire and the city of Soissons would be relieved of the danger of bombardment.
Allied operations on two widely separated fronts—the British on the north of the Lys salient, and the French between the Aisne and the Oise—had increased the difficulties of the Germans in these areas.
Lassigny was seriously threatened by the capture of Fresmières (on the Roye highroad two and a half miles to the north) by the advance of Foch's troops to the western outskirts of the town, and the occupation of the Thiescourt Wood.
On the night of August 18, 1918, the French launched an attack on a front of about fifteen miles east of Ribécourt and across the Oise to Fontenoy, six miles west of Soissons. The fighting, vigorously pushed on the following day, resulted in notable gains for the Allied arms. The capture of the village of Rimprez, on the west bank of the Oise on the Noyon-Compiègne road, was followed by an advance of two miles northward to the southern edge of Dressincourt. Equally important gains were made at other points in the line of attack. The plateau west of Nampcel and Morsain and several other villages were carried by storm. In the course of the fighting the French captured over 2,000 prisoners, including several battalion commanders.
In the Lys salient the British continued the irresistible drive forward. Marshal Haig's advance was on a front of nearly six miles. His line was carried up to the town of Merville and to the north-and-south road through the town from Les Purebecques on the north to Paradis to the south.
The victories of the French troops between the Oise and the Aisne gave them possession of the Oise Valley as far as Mont Renaud. General Mangin, who carried out these successful operations, was now in a position to force the enemy to resort to desperate measures to escape a serious defeat. His artillery now commanded all roads of importance, and the only exit available for the Germans from the region of Noyon and Lassigny was a narrow-gauge line running north to Ham by way of Guiscard and the highroad running in the same direction. Von Hutier had either to check Mangin's advance, or choose this narrow outlet for extricating his troops and material. Rather than face this alternative, the Germans were offering a desperate resistance in an endeavor to hold on to their present lines, hoping against hope that something might occur that would enable them to shake off the Allies' strangle hold.
General Debeney's advance on Lassigny and Roye had slackened up owing to the stout opposition offered by the enemy, but he continued to make steady progress.
In the early morning of August 20, 1918, General Mangin began an operation between the Aisne and the Oise southeast of Noyon and northwest of Soissons that achieved a splendid success. Striking on a fifteen-and-a-half-mile front he smashed into the German line to an average depth of two and a half miles, capturing seven towns and over 8,000 prisoners.
By these operations General Mangin wrested from the Germans at Cuts and Mont de Choissy all the heights remaining south of the Oise in that region. The French batteries now commanded a wide sweep of territory and most of the important roads. General Mangin's right, firmly established on the heights around Fontenoy, now began to drive the enemy from the elevated ground south of the Oise, leaving them no option but to cross the river, or retreat toward the east. The Germans fought desperately to hold their ground, relying principally on their vast number of machine guns. During the night, in anticipation of General Mangin's attacks, they had received reenforcements brought up from the Soissons front in motor lorries to help meet the shock of the French troops. They fought with dogged determination, but from the start their position was hopeless. Their artillery fire was of the feeblest and they had practically no help from airplanes.