He was loyal to the Ottomans throughout World War I, during which the Ottomans were part of the Central Powers alliance. While he was based in Tulkarm, al-Hashimi was asked by Faisal to join the Sharifian Army, but he refused, stating he could not abandon his military duties. Despite his Arab nationalist affiliations, he opposed a plot by the nationalists to kill Jamal Pasha, despite his awareness that Jamal Pasha was intent on crushing the Arab nationalist movement. In 1917, he commanded an Ottoman division at Galicia during the Russian offensive. He was recognized for his successes against the Russians during that campaign, including by German Emperor Wilhelm II, and subsequently promoted to major general.