The historical consensus about the Nazis' "Sieg Heil" yell is that Hitler copied it from Mussolini's fascists with whom he shared a taste for grandiose thuggery. But US wartime intelligence had an alternative theory - it was borrowed from American cheerleaders.

That unlikely claim is one of many observations and anecdotes in a bizarre document recently declassified by the CIA - a pyschological profile of Hitler assembled in 1942 by one of the CIA's forerunners, the Office for Strategic Services (OSS).

The profile relies heavily on the personal observations of one of Hitler's best friends in the 1920s, Ernst Hanfstaengl, whom the future Führer knew as "Putzi" but who appears in the profile under the codename, Dr Sedgwick. The Hitler file also strays into psychoanalytical speculation about the Nazi leader's sexuality based on his fondness for circuses and whips.

In an analysis of Hitler's taste in music, the document naturally mentions Wagner, Strauss and Liszt. Then comes the extraordinary claim about the origin of the Hitler salute: "In 1923 he adored American football marches and college songs. The 'Sieg Heil!' used in all political rallies is a direct copy of the technique used by American football cheerleaders. American college type of music was used to excite the German masses who had been used to very dry-as-dust political lectures."

The OSS also mined Hitler's other tastes in entertainment for insights into his character. "He loves the circus. The thrill of underpaid performers risking their lives is a real pleasure to him," the document notes. "During the summer of 1933 he went several times to the circus and on the next day he would send flowers and chocolates to the value of several hundred marks to the girls who had performed dangerous feats before him... He does not care much for wild animal acts, unless there is a woman in danger."

The profile adds: "He likes comedies and will laugh heartily at a Jewish comedian. He even likes a Jewish singer and will say afterward that it is too bad he or she is not an Aryan!" In a rumour apparently passed on by Hanfstaengl, it notes: "There is reason to believe that Heinrich Hoffman (Hitler's official photographer) also shows him pornographic photographs and movies." The analysis delves further, suggesting that Hitler was a repressed bisexual whose "sexual situation is untenable and even desperate".

The archive even provides insight into the toothbrush moustache. When Hanfstaengl declared it ugly, Hitler replied: "Do not worry about my moustache. If it is not the fashion now, it will be later because I wear it."

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