By January 1918 he was serving on the Turkish cruiser Midilli, ex-SMS Breslau, when it sortied into the Aegean Sea to attack British troop transports.
The surviving 162 crewmembers, including trainee naval engineer Hans Voss, were rescued by a British destroyer and became prisoners of war.
From October 1938 to July 1943 Voss was a consultant in the Operations Department of the Seekriegsleitung (Sea Combat Command or Naval General Staff).
From August 1943 to October 1944 Voss was Chief of the Higher Shipyard Staff Ostland (the German name for the Baltic states of Latvia, Lithuania, Estonia and portions of Northern Russia).
Voss subsequently spent time in the British prisoner of war camp at Island Farm, Wales, and also Grizedale Hall, in the Lake District.