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.
After earning his pilot's license in 1932, Henne was called up by the Luftwaffe during World War II, but was disqualified from service because of the head trauma and concussions he had experienced as a racing driver.