Tukhachevsky succeeded eventually in reorganizing his eastward-retreating forces, but not in regaining the initiative. In September, he established a new defensive line near Grodno. In order to break it, the Polish army fought the Battle of the Niemen River (September 15–21), once again defeating the Red Army. After the Battle of the Szczara River, both sides were exhausted. On October 12, under heavy pressure from France and Britain, a ceasefire was signed. By October 18, the fighting was over, and on March 18, 1921, the Treaty of Riga was signed, ending hostilities.