 The command structure had a negative impact on German naval warfare in World War I, as a professional head of the Imperial Navy, similar to the First Sea Lord, was not established until August 1918.After the war and the German Revolution of 1918–19, the Admiralty Staff became subordinate to the Naval Office and was finally disestablished by order of the German President.After the German unification of 1871, a united Imperial Navy was established as successor of the Prussian Navy and the North German Federal Navy, from 1 January 1872 under the authority of the German Imperial Admiralty ("Kaiserliche Admiralität") led by Minister of State Albrecht von Stosch.