Kammala jumla mai zuwa: A lokacin da aka tattara, an sanya XX Corps zuwa rundunar soja ta 8 don kare Gabashin Prussia yayin da sauran sojojin suka aiwatar da shirin Schlieffen a watan Agustan 1914. Ya shiga cikin yaƙe-yaƙe na Gumbinnen, Tannenberg da 1st Masurian Lakes. Nan da nan bayan 1st Masurian Lakes ya shiga rundunar soja ta 9 a Lower Silesia inda ya yi yaƙi a
Yaƙin Kogin Vistula. A watan Mayu na 1915 ya dawo tare da Rundunar Soji ta 8 kuma a ranar 26 ga Mayu kwamandan Rundunar XX, Janar der Artillerie Friedrich von Scholtz, ya zama kwamandan rundunar, yayin da yake rike da umarnin rundunarsa a lokaci guda. A ranar 29 ga Satumba, 1915, an rushe hedkwatar rundunar ta 8. A ranar 18 ga Satumba, 1915, an inganta XX Corps don samar da "Armee-Gruppe" Scholtz, daga baya "Armee-Abteilung" Scholtz, a matsayin wani ɓangare na Sojojin Niemen.