At the outbreak of the First World War, Seeckt held the rank of lieutenant colonel and served as chief of staff for Ewald von Lochow in the German III Corps. On mobilisation, the III Corps was assigned to the 1st Army on the right wing of the forces for the Schlieffen Plan offensive in August 1914 on the Western Front.[9] Early in 1915, after they were attacked by the French near Soissons, Seeckt devised a counterattack that took thousands of prisoners and dozens of guns.[10] He was promoted to colonel on 27 January 1915.[2] In March 1915, he was transferred to the Eastern front to serve as chief of staff to General August von Mackensen of the German Eleventh Army.