The regiment then returned to 4th Infantry Division, and headed for Belgium as part of the Operation Cobra, moved into Belgium on 6 September 1944, and entered Germany on 11 September 1944. On 14 September its 3d Battalion broke through the Siegfried Line near Buchet, but neither the regiment nor other formations of 4th Division were able to exploit a success because of rough terrain lacking good roads, bad weather hampering air and artillery support and several other causes. These developments were described by Ernest Hemingway in his article "War in the Siegfried Line".