From 29 May 1940 until 7 April 1945 Christiansen was "Wehrmachtsbefehlshaber in den Niederlanden" (Supreme Commander of the "Wehrmacht" in the Netherlands,) and from 10 November 1944 until 28 January 1945 supreme commander of the 25th Army.
From 29 May 1940 until 7 April 1945 Christiansen was "Wehrmachtsbefehlshaber in den Niederlanden" (Supreme Commander of the "Wehrmacht" in the Netherlands), and until June 26,1943, was concurrently still Korpsführer of the NSFK. In addition, from 10 November 1944 until 28 January 1945 supreme commander of the 25th Army.