Polizei Bayern
Soon after he was released from internment in November 1919, Fortner transferred from the Reichswehr to the Bavarian State Police and over a period of 15 years rose to the rank of "Polizei-Oberst" (Police Colonel) before joining the Wehrmacht soon after its creation in 1935 with the rank of "Oberst" (Colonel), and was appointed as the commander of the Kassel military district.