The Duchy of Mantua was a duchy in Lombardy, Northern Italy. Its first duke was Federico II Gonzaga , member of the House of Gonzaga that ruled Mantua since 1328.  The following year, the Duchy also acquired the March of Montferrat , thanks to the marriage between Gonzaga and Margaret Paleologa , Marchioness of Montferrat .
The Congress turned it into an independent country under the name Duchy of Brunswick. Charles II (1815–1830) [ edit ] The underage Duke Charles , the eldest son of Duke Frederick William (who had been killed in action), was put under the guardianship of George IV , the Prince Regent of the United Kingdom and Hanover.