Apparently she had no qualms about abandoning court elegance, leisures and courtesies to dress in military armor and fight on the front line alongside her husband; her presence was to impress and greatly encourage the troops, if Anna Comnena described her in her book “like another Pallas, if not a second Athena”.
Thanks to her, the exponents of the old Lombard court supported the Norman monarchy, and it was always thanks to his mediation and his advice that Roberto the Guiscardo obtained the alliance with the papacy: he was in fact among the promoters of the Council of Melfi, during which Pope Nicolò recognized the conquests of the Guiscardo as his legitimate possession and appointed him Duke of Puglia and Calabria.
He had an intelligence always greedy for knowledge, in the last years of his life he dedicated himself to deepening his medical studies, of which he had received the first rudiments as a girl, during his stay in the monastery of S. Giorgio; apparently she was also a student of Trotula de Ruggiero, another woman with enviable acumen and culture for the time, as well as the first female doctor in history.
After the death of Roberto il Guiscardo, his medical knowledge led the duchess’s detractors to accuse her of the attempted poisoning of Boemondo di Taranto, son of Roberto il Guiscardo and his first wife. It is not known if this allegation was true or not, but certainly in the years to come Sichelgaita and Boemondo found an agreement, these ceded the succession of the duchy to the first son of Roberto il Guiscardo and Sichelgaita, the future Duke Ruggero Borsa.
The beautiful Sichelgaita, princess, strategist, wife, doctor, was also known for her ardent faith in God and for loyalty to the Church of Rome. She used to deepen the study of the Holy Scriptures and let herself be guided in the spiritual life by her wise cousin Desiderio, future pope Victor III, prior of the Abbey of Montecassino; Roberto il Guiscardo also had full confidence and almost filial affection towards Desiderio, to whom he did not disdain to ask for advice and prayers. Such was the link between the dukes and the Abbey, which, in agreement with the Benedictine bishop Alfano I, was inspired by its architectural structure for the construction of the imposing Cathedral of San Matteo in Salerno. Sichergaita died in 1090 and was buried in Montecassino, in that same Abbey that had welcomed her so many times in prayer.