Reinhard Scheer
In 1900, Weizsäcker joined the Imperial German Navy to become an officer, serving mainly in Berlin. In 1916, he served as Flag Lieutenant to Admiral Reinhard Scheer aboard the German flagship during the Battle of Jutland. In 1917, during the latter portion of the First World War, he earned the Iron Cross (both classes) and was the next year was promoted to "Korvettenkapitän" (corvette captain) (equivalent to the British and American rank of lieutenant commander).