With numerous British war films being produced in the 1950s, Diffring's blond hair, blue eyes and his chiselled features saw him often cast as villainous German officers, in Albert R.N. (1953) and The Colditz Story (1955). Some of his more notable roles as German characters were in The Heroes of Telemark (1965), The Blue Max (1966), Where Eagles Dare (1968), Operation Daybreak (1975) (as SS officer Reinhard Heydrich) and the match commentator in Escape to Victory (1981), though he also played a Polish parachutist in The Red Beret (1953). In 1983 he played Hitler's foreign minister Joachim von Ribbentrop in the American mini-series The Winds of War. In the Italian war movie Uccidete Rommel, shot in an Egyptian desert in 1969, he played the role of a British officer of the SAS.