One of history's most brutal tyrants was a diagnosed schizophrenic on a mission to avenge his childhood years of repressed rage, according to Henry Murray, an American psychologist and a Harvard professor.

In 1943, the US Office of Strategic Services, a precursor to the CIA, commissioned Murray to study Adolf Hitler's personality to try to predict his behavior. In his 229-page report, Analysis of the Personality of Adolf Hitler, Murray described Hitler as a paranoid “utter wreck” who was “incapable of normal human relationships.”

“It is forever impossible to hope for any mercy or humane treatment from him,” Murray wrote.

After a frustrating childhood, Hitler felt obligated to exert dominance in all things.​

Hitler suffered from intolerable feelings of inferiority, largely stemming from his small, frail, and sickly physical appearance during his childhood.

He refused to go to school because he was ashamed that he was a poor student compared to his classmates.

His mother appeased him by allowing him to drop out.

“He never did any manual work, never engaged in athletics, and was turned down as forever unfit for conscription in the Austrian Army,” Murray writes.

Hitler managed his insecurities by worshiping “brute strength, physical force, ruthless domination, and military conquest.”

Even sexually, Hitler was described as a “full-fledged masochist,” who humiliated and abused his partners.

Much of his wrath originated from a severe Oedipus complex.​

As a child, Hitler experienced the Oedipus complex — love of mother and hate of father — which he developed after accidentally seeing his parents having sex, Murray's report says.

Hitler was subservient and respectful to his father but viewed him as an enemy who ruled the family “with tyrannical severity and injustice.” According to the report, Hitler was envious of his father's masculine power and dreamed of humiliating him to re-establish “the lost glory of his mother.”

For 16 years, Hitler did not exhibit any form of ambition or competition because his father had died and he had not yet discovered a new enemy.

Hitler frequently felt emasculated.

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Another blow to Hitler's masculinity: He was “incapable of consummating in a normal fashion,” old sexual partners shared with Murray.

“This infirmity we must recognise as an instigation to exorbitant cravings for superiority. Unable to demonstrate male power before a woman, he is impelled to compensate by exhibiting unsurpassed power before men in the world at large,” he writes.

As mentioned, when Hitler did have sexual relations with a woman, he exhibited masochistic behaviours. Hitler was said to have multiple partners, but eventually married his long-term mistress, Eva Braun, hours before the two committed suicide together in his Berlin bunker.

He suffered from indecisiveness and collapsed under pressure.

Even at the peak of his power, Hitler suffered from frequent emotional collapses from a guilty conscience.

“He has nightmares from a bad conscience, and he has long spells when energy, confidence, and the power of decision abandon him,” Murray writes.

According to Murray, Hitler's cycle from complete despair to reaction followed this pattern:

An emotional outburst, tantrum of rage, and accusatory indignation ending in tears and self-pity.

Succeeded by periods of inertia, exhaustion, melancholy, and indecisiveness.

Followed by hours of acute dejection and disquieting nightmares.

Leading to hours of recuperation.

And finally confident and resolute decision to counterattack with great force and ruthlessness.

The five-step evolution could last anywhere from 24 hours to several weeks, the report says.

He was ashamed of his mixed heritage.

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Hitler valued “pure, unmixed, and uncorrupted German blood,” which he associated with aristocracy and beauty, according to Murray.

He offered the following explanation of Hitler's contempt for mixed blood:

As a boy of twelve, Hitler was caught engaging in some sexual experiment with a little girl; and later he seems to have developed a syphilophobia, with a diffuse fear of contamination of the blood through contact with a woman.

It is almost certain that this irrational dread was partly due to the association in his mind of sexuality and excretion. He thought of sexual relations as something exceedingly filthy.

Hitler denied that his father was born illegitimately and had at least two failed marriages, that his grandfather and godfather were Jews, and that one of his sisters was a mistress of a wealthy Jew.

He focused his hatred on Jews because they were an easy target.

Murray explains that Jews were the clear demographic for Hitler to project his personal frustrations and failings on because they “do not fight back with fists and weapons.”

The Jews were therefore an easy and non-militarised target that he could blame for pretty much anything, including the disastrous effects after the Treaty of Versailles.

Anti-Semitic caricatures also associated Jews with several of Hitler's dislikes, including business, materialism, democracy, capitalism, and communism. He was eager to strip some Jews of their wealth and power.

He was moody, awkward and received compliments on his eye-colour.

Adolf Hitler is widely held responsible for up to 11 million Holocaust deaths and the Second World War which killed up to 80 million (Getty)

According to Murray's report, Hitler received frequent compliments on his greyish-blue eyes, even though they were described as “dead, impersonal, and unseeing.”

He was slightly below average in height and had a receding hairline, thin lips, and well-shaped hands.

Murray notes that the merciless Nazi leader was known to offer a weak handshake with “moist and clammy” palms and was awkward at making small talk.

Sources say Hitler appeared to be shy or moody when meeting people and was uncoordinated in his gestures. He was also incredibly picky about his food.