During the Franco-Prussian War, the division was a mixed unit, with Hannoverian, Brunswick and Westphalian elements.
It was subsequently reorganized so that it was recruited primarily from the former Kingdom of Hannover, which had become the Prussian Province of Hanover after 1866, along with the Duchy of Brunswick.
During the Franco-Prussian War, the 20th Infantry Division fought in the battles of Mars-la-Tour and Gravelotte, and then in the Siege of Metz.
It then fought in the Loire Campaign, including the battles of Beaune-la-Rolande, Orléans, Beaugency-Cravant, and Le Mans.
It returned to the Western Front and after a period in the trenches saw action in the Battle of Passchendaele and the German 1918 Spring Offensive.