Charles was never Duke of Mantua since he died at Cavriana six years before his father. When the latter died in 1637, Charles's eight-year-old son, Charles II, became Duke of Mantua, his widow Maria acting as regent. His daughter Eleonora became Holy Roman Empress.
Family
In December 1627 he married his cousin Maria Gonzaga, the marriage being arranged by Vincenzo II Gonzaga.
Bourne, Molly (2016). "From court to cloister and back again: Margherita Gonzaga, Caterina dé Medici and Lucrina Fetti at the convent of Sant'Orsola in Mantua". In Cavallo, Sandra; Evangelisti, Silvia (eds.). Domestic Institutional Interiors in Early Modern Europe. Routledge. p. 153-180.
Sanders, Donald C. (2012). Music at the Gonzaga Court in Mantua. Lexington Books.
Ward, A.W.; Prothero, G.W.; Leathes, Stanley, eds. (1934). The Cambridge Modern History. Vol. XIII. Cambridge University Press.