Her marriage probably signaled the subordination of Burgred to his father-in-law and the Saxon kingdom at a time when both Wessex and Mercia were suffering Danish (Viking) raids.
In 868 she witnessed a West Saxon charter and made a grant of fifteen hides of land in her own name in Berkshire, rare for a queen of the period to do so.
[1][2] One item that is believed to have been hers, a gold ring inlaid with niello, inscribed with the words Æthelswith Regina, survives in the British Museum.
Burgred's reign lasted until 874 when the Vikings drove him from the kingdom and he fled to Rome with Æthelswith.
Æthelswith lived on in Italy for another decade, before dying while on a pilgrimage in Pavia in 888[3] and was buried in the monastery of San Felice.