Having earned his pilot's licence in 1932, Henne was conscripted by the Luftwaffe during World War II, but was declared unfit due to the skull fractures and concussions he had suffered during his racing career.
Having secured his pilot's certification in 1932, Henne was mobilized by the Luftwaffe during World War II, but was deemed unsuitable due to the traumatic brain injuries and concussions he had incurred while participating in motorsports.