South of the Marne the newly-formed 9th Army (General de Mitry), attacked at 6 a.m. The enemy, fully occupied elsewhere, did not offer serious resistance, and De Mitry’s Army reached the Marne in the middle of the afternoon with comparatively little difficulty.
North of the Marne the 5th Army attacked on the St. Euphraise-Belval front, with a British corps astride of the Ardre, and in spite of vigorous enemy resistance and several counter-attacks, had advanced by evening to the line: St. Euphraise, the western outskirts of Courmas, eastern outskirts of Courton and Marfaux, Nappes, the northern and north-eastern outskirts of Courton Wood, the eastern outskirts of La Neuville and Belval, and to the south-east of Reuil.
On the 21st, the Germans made another powerful effort with four fresh divisions. North of the Ourcq they counter-attacked Mangin’s Army with three divisions supported by tanks, in spite of which, the French continued to advance, occupying Berzy-le-Sec and reaching Chaudun.
North of the Marne the enemy energetically opposed the Allies’ advance and counter-attacked on both banks of the Ardre, but were unable to prevent the French, British and Italian troops from taking St. Euphraise and Bouilly and progressing in the Courton Woods.
The situation of the enemy was still critical, as their divisions engaged in the bottom of the Château-Thierry “pocket,” where the pressure from Degoutte’s and De Mitry’s Armies was increasing, were in danger of being cut off. A further retreat was therefore ordered. Overcoming all difficulties, Franco-American battalions crossed the Marne near Château-Thierry, now re-occupied by the 39th Division. Harrying the retreating enemy and advancing in places as much as six miles, they reached by evening the region of Brény-Chartèves.
On the 22nd, the front was quiet between the Aisne and the Ourcq, but between the Ourcq and the Marne violent enemy counter-attacks temporarily drove back the Allies. However, at the end of the day the Allies had progressed beyond the Château-Thierry-Soissons road. On the Marne, French troops, moving eastwards under enemy artillery and machine-gun fire, enlarged their bridgehead on both banks. The slopes of Rozay, Passy and Marcilly and the Courcelles Signal were carried at the point of the bayonet, while several detachments pushed forward to Port-á-Binson and to the south of Vandières.
On the 23rd, from the Aisne to the Ourcq, the enemy resisted obstinately, and the Allies made but little progress; numerous enemy machine-gun nests were encountered at Villemontoire and Tigny, while their artillery had also been reinforced.
From the Ourcq to the Marne the German resistance stiffened and occasionally counter-attacks were made, notwithstanding which the Franco-American troops progressed in the Fère and Ris Woods, and along the narrow passage which separates them. An advance was also made higher up the river near Reuil, but the attack by the 77th Division at this point failed to drive back the enemy. Some progress was made in the Ardre valley, in spite of enemy reinforcements.
On the 24th, between the Ourcq and the Marne, the Allies advanced three and a half miles in the centre and about two miles on the wings, the front in the evening, being: Nanteuil, the eastern outskirts of La Tournelle Wood, Beuvardes, Le Charmel and Chassins.
On the 25th, north of the Ourcq, hard fighting took place around Villemontoire, which was finally carried by the 12th Division. Elsewhere the 11th Corps, forming the right of the 10th Army, recaptured Oulchy-le-Château, Oulchy-la-Ville and Cugny after desperate combats, the enemy having been reinforced by three fresh divisions. South of the river progress was also made between Coincy and Le Charmel, while Beuvardes was recaptured.