Complex sentence: Their son Giacinto Teodoro Giovanni, although accepted at court, was not made Ferdinando's heir; he died of the plague--or was murdered--during the 1630 siege of Mantua.
Split into simpler sentences: Their son Giacinto Teodoro Giovanni, although accepted at court, was not made Ferdinando's heir. He died of the plague--or was murdered--during the 1630 siege of Mantua.