In response to this important alliance, Charles was able to remove the French from Casale, then agreed with Louis XIV of France that the Monferrato should not be controlled by Spain but would remain with the Gonzaga family. Charles kept a lover, Margaret Oak and sometimes neglected Isabella, but they had one son, Charles (31 August 1652–5 July 1708) who in 1665 became Duke of Mantua. [citation needed]
Widowhood
Duke Charles died suddenly on 14 August 1665, when Isabella assumed the role of Regent on behalf of her thirteen-year-old son, to be assisted in the affairs of government by Count Charles Bulgarini, a nobleman of Jewish origins with whom Isabella had long had an amorous relationship.[2]
Charles reached his majority and attained full ducal power in 1670. A year later, on the advice of his mother, he married Anna Isabella Gonzaga of the Guastalla branch of the Gonzagas. Isabella retired to private life in the Goito palace, then on 16 December 1671, on the orders of the emperor, she entered a convent where she remained for the rest of her life. Isabella died in 1685. [citation needed]
Generations are numbered by male-line descent from Frederick III, Holy Roman Emperor. Later generations are included although Austrian titles of nobility were abolished and outlawed in 1919.