Complex sentence: In Berlin he continued as the Acting Governor of German New Guinea and was officially appointed Governor on 14 December 1917, as Hahl was now declared unfit by the Imperial Colonial Secretary, Wilhelm Solf.
Split into simpler sentences: In Berlin he continued as the Acting Governor of German New Guinea. On 14 December 1917, Haber was officially appointed Governor, as Hahl was now declared unfit by the Imperial Colonial Secretary, Wilhelm Solf.