Empress
After this wait, Emperor Frederick II summoned his bride to Worms, where their official wedding took place and Isabella was crowned at Worms Cathedral by Archbishop Siegfried III of Mainz. Researchers disagree on the date of this double event. Alison Weir and Mary Anne Everett Green date it 20 July 1235. On the other hand, Kate Norgate, author of the article on Isabella in the Dictionary of National Biography, writes about Sunday 15 July, while James Panton lists both dates as possible. Wedding celebrations lasted for four days, and they were attended by "four kings, eleven dukes, counts and margraves, thirty or fewer prelates and minor nobles".
On 14 August, Emperor Frederick II called an assembly to which representatives from all over the Empire were invited; they met the new empress and brought her their congratulations. Isabella (or Elizabeth, as some of her husband's subjects called her) seems to have been a very dignified and beautiful woman. Frederick was delighted with his new wife, but immediately after the wedding he got rid of Isabella's English entourage "of both sexes", leaving only her nurse Margaret Biset and one maid with her, and transferred her to seclusion in Hagenau, where the couple spent most of the winter. Earlier, the English embassy, which arrived with Isabella, left for their homeland; they brought gifts to their king from the emperor, among whom were three living leopards —animals depicted on the coat of arms of the English king.
Soon after the wedding, Emperor Frederick II was forced to leave and consign his wife to the care of his son Conrad. In early 1236, Isabella and her husband visited Ravenna; part of the year the imperial couple spent in Italy, after which they returned to Germany. Already being married, Isabella continued to maintain a relationship with her brother King Henry III, including keeping up their correspondence, in which they communicated as warmly as strict etiquette allowed. Cordial correspondence with the English king was conducted by the Emperor as well, but the name of his wife was mentioned in the letters only occasionally and strictly with regard to political issues. In July, Emperor Frederick II was preparing for a military campaign and was forced to leave his wife in Germany for almost a year.
By Michael's Day, Emperor Frederick II returned to Lombardy, where he summoned his wife and where he spent the winter with her. In September 1238, the emperor sent his wife to Andria, where Isabella remained until December, when the archbishop of Palermo escorted her back to Lombardy. In early 1239, Isabella spent some time in Noventa Padovana while her husband was in Padua; in February 1240, she returned to southern Italy, where the emperor soon arrived.
Emperor Frederick II, it seems, respected and loved his wife, but in a quite strange manner, taking care of her safety and surrounding her with luxury and splendor, but keeping her at a distance from himself and the company of his "harem", which included women from Arabia. In addition, James Panton writes that the empress was forbidden to communicate with all men, except for the black eunuchs around her. Isabella's brother King Henry III complained that his sister was never allowed to "wear her crown" publicly or appear as empress at public meetings. In 1241, when her second brother, Richard of Cornwall, went to visit Frederick on his way back from the Holy Land, only "after a few days" was he able "with the permission of the emperor and of his own free will" to visit his sister's chambers. Frederick did not allow Isabella to meet her brother at court.
Isabella died in childbirth at Foggia near Naples in 1241. Alison Weir dates Isabella's death between 1–6 December, while Kate Norgate and Mary Anne Everett Green believe that she died on 1 December. Frederick II at the time of his wife's death was in Faenza, and Isabella's dying words were a request to her husband to continue to maintain friendly relations with her brother King Henry III. Isabella was buried with full honors at Andria Cathedral near Bari beside Frederick's previous wife, Queen Isabella II of Jerusalem.
King Henry III was deeply saddened and shocked by his sister's death. He ordered his almoner to distribute, "for the soul of the empress, our late sister," over £200 in alms at Oxford and Ospringe, and the same amount was distributed in London and Windsor. Matthew Paris lamented the death of Isabella, calling her "the glory and hope of England".
