On October 18, 1914, shortly after the outbreak of the First World War, Hippel volunteered for service in the Schutztruppe for German East Africa, where he served under General Paul von Lettow-Vorbeck in the East African theatre, where Lettow-Vorbeck had conducted a guerrilla campaign against Allied colonial troops.

Since the project was top secret, this unit was designated "Special Duty Training and Construction Company" (Lehr- und Baukompanie) to mask its true function.

By mid-year, small teams of commandos had entered Poland to infiltrate key factories, mines and power stations.

Meanwhile, other Brandenburgers slipped across the frontiers, infiltrated behind Polish defensive positions and seized crucial bridges across the river Vistula.

Hippel was sent to North Africa in February 1943, where he commanded a German-Arab unit in Tunis, surrendering to the Allied troops with the rest of the Axis forces in Tunisia in May 1943.