What helmet typically associated with the Prussian Army was replaced by a steel helmet during World War I?
Stahlhelm Stahlhelm (plural "Stahlhelme") is German for "steel helmet". The Imperial German Army began to replace the traditional boiled leather Pickelhaube (spiked combat helmet) with the Stahlhelm during World War I in 1916. The term "Stahlhelm" refers both to a generic steel helmet, and more specifically to the distinctive (and iconic) German design.
3rd Army (German Empire) The 3rd Army (German: 3. Armee / Armeeoberkommando 3 / A.O.K. 3 ) was an army level command of the German Army in World War I. It was formed on mobilization in August 1914 seemingly from the II Army Inspectorate. The army was disbanded in 1919 during demobilization after the war.