Rundstedt served as 22nd Division's chief of staff during the invasion of Belgium, but he saw no action since his Division was held in reserve during the initial advance. In December 1914, suffering from a lung ailment, he was promoted to Major and transferred to the military government of Antwerp. In April 1915 his health recovered, and he was posted as chief of staff to the 86th Infantry Division which was serving as part of General Max von Gallwitz's forces on the Eastern Front. In September he was once again given an administrative post, as part of the military government of German-occupied Poland, based in Warsaw. He stayed in this post until November 1916, until he was promoted by being made chief of staff to an Army Corps, XXV Reserve Corps, which was fighting in the Carpathians. Here he saw much action against the Russians. In October 1917 he was appointed chief of staff to LIII Corps, in northern Poland. The following month, however, the October Revolution led to the collapse of the Russian armies and the end of the war on the eastern front. In August 1918 Rundstedt was transferred to the west, as chief of staff to XV Corps in Alsace, under General Felix Graf von Bothmer. Here he remained until the end of the war in November. Bothmer described him as "a wholly excellent staff officer and amiable comrade." He was awarded the Iron Cross, first class, and was recommended for the Pour le Mérite, but did not receive it. He thus ended World War I, although still a major, with a high reputation as a staff officer.