A long-standing but ultimately unsupported hypothesis suggested that the Germans believed that the British Prime Minister, Winston Churchill, was on board the flight. Churchill's history of World War II suggested that the Germans targeted the commercial flight because the British Prime Minister's "presence in North Africa the 1943 Casablanca conference had been fully reported," and German agents at the Lisbon airfield mistook a "thickset man smoking a cigar" boarding the plane for Churchill returning to England. The death of the fourteen civilians including Leslie Howard "was a painful shock to me," Churchill wrote; "the brutality of the Germans was only matched by the stupidity of their agents".