Born in Danzig (Gdańsk), Below was appointed to the command of XXI Corps in 1912. In this capacity, he fought along with the 6th Army on the Western Front at the beginning of World War I. His corps was transferred in 1915 to the Eastern Front where it participated in the Second Battle of the Masurian Lakes. Below was awarded the Pour le Mérite on 16 February 1915 for successful campaigns on the Western Front and in the Second Battle of the Masurian Lakes.