 On 24 March 1865, with the fleet having returned to its demobilized, peacetime status, Jachmann was given command of the "Marinestation der Ostsee" (Naval Station of the Baltic Sea).Later that year, Jachmann moved the fleet to its new main base at Kiel in the newly annexed Duchy of Schleswig.There, he was responsible for establishing the new base, the land defenses for which were established at Hörup Haff and Holtenau Bay under the direction of Generals Helmuth von Moltke, the Chief of the General Staff, and Albrecht von Roon, the Prussian Minister of War.