On September 27, 1918, the 105th and 106th Infantry Regiments advanced 1,000 yards to capture the German strong points at the Knoll, Gillemont Farm, and Quennemont Farm. The New Yorkers encountered stiff resistance and sustained heavy casualties. At the end of the day, the strong points remained in enemy hands despite the loss of 317 Americans. The men were relieved by the 107th and 108th Infantry Regiments the following day.
On September 29, the 107th and 108th Infantry Regiments resumed the assault toward the Hindenburg Line. First, they had to secure the objectives of the previous day. The coordinated assault soon deteriorated into small battles. Small groups or individuals took heroic actions against enemy machine gun nests and trenches. The 107th sustained the highest number of casualties –337 killed and 648 wounded–of any American regiment in a single day during the war. Four men of the regiment were awarded the Medal of Honor.
In desperate fighting, General O'Ryan employed all four regiments of the 27th Division, leaving only one battalion of engineers in reserve. By the end of the day, the 27th Division had made significant advances but still faced several pockets of enemy resistance.
On October 1, the 3rd Australian Division prepared to "leapfrog" the Americans and continue the breakthrough. Following the breaking of the Hindenburg Line, the 27th was relieved. With the loss of its last and best line of fortifications, the German Army began a general retreat toward the Le Selle River. The Allies remained in close pursuit.
The 27th rejoined the fight at the Le Selle River on October 17, again forcing the Germans to withdraw. With their armies in retreat, the Germans agreed to an armistice.