His marriage to Costanza of Sicily was to seal the peace between the Holy Roman Empire and Sicily. The pope did not approve of the marriage and rumours were circulated that Costanza was a nun and had been made to forswear her vows. She had indeed lived in a convent in Palermo and was religious but she was not a nun; also, she was heir to her childless nephew.
Heinrich VI was eleven years younger than his bride of about thirty-one years and he was regarded as "not affable or benevolent with the peoples". Costanza, who was tall and fair and wealthy,
dutifully married him, after which they were crowned with the historic crown of Lombardy.

The pope placed the officiating Patriarch of Aquileia under the church's interdict and Heinrich marched towards Rome. However, news came that Jerusalem had fallen to Saladin and then that the pope had died. Heinrich's father, the aged Emperor Friedrich I Barbarossa, went on crusade but drowned in Asia Minor in 1190.
In 1189 Costanza's nephew, the King of Sicily, had died, making Heinrich and Costanza King and Queen of Sicily. Now that his father had died, Heinrich VI became Emperor as well. However, the Sicilians wanted Tancred, an illegitimate member of the Sicilian royal family, as king; and the new pope wanted Sicily to be separated from the Holy Roman Empire.
In the spring of 1191, Heinrich and Costanza came to Rome for their coronation. In May, Heinrich besieged Naples. The city of Salerno asked Costanza to come and visit; however, when she did, the
people then came to realise what kind of man Heinrich VI was and so handed her over to Tancred. Nevertheless, the latter received her with honour and after several months sent her back to her husband.
Three years later, after Tancred's death, Heinrich VI resumed his attack to conquer Sicily. He succeeded and, with promises of a general amnesty, was invested with the royal regalia on 26 December 1194. The celebrations were barely ended when the Sicilian nobles and clergy still present were seized by Heinrich VI. Claiming that a conspiracy on behalf of Tancred's young son had been detected, he had the child blinded and castrated while all those nobles present at Tancred's
coronation were burnt alive.
What Heinrich VI as yet did not know was that, also on 26 December 1194, his forty-year-old wife had at last given birth to a child, the future Emperor Friedrich II. Costanza, hoping to give birth in Sicily, was on her way from Germany; but in Jesi near Ancona it became obvious that her time had come. To prevent rumours that she was not the mother (after all, at forty she was regarded to be too old to give birth to a first child) she had a tent erected in the market-place and requested
the matrons of the town to attend the birth.
Costanza then went to Sicily where they underwent another coronation, after which Heinrich VI set out for Germany leaving Costanza as head of a regency council. The main reason for his journey
was to have his baby son elected as his imperial successor. In this he succeeded but his cruelty had left a difficult legacy for his wife in Sicily. A rebellion broke out which, returning with an army for his crusade, Heinrich VI put down. Again hostages were cruelly blinded while rebellion leaders were tortured in the presence of both Heinrich VI and Costanza.
Convinced that rebellions were now out of the question, he was ready to sail for the Holy Land. However, once more the nobles did rise against him, but this time he adopted a more conciliatory
attitude and succeeded to regain control. However, suspecting that his wife had played a part in this last revolt, he had her confined in the Palace of Palermo. He may have considered even further cruelties but, suddenly, after a short illness, he died aged only thirty-one.
 
 

Source: Leo van de Pas