The legendary Renaissance warrior Giovanni de’ Medici did not die from an improperly amputated leg, as widely believed, but an infection.

Also known as “Giovanni dalle Bande Nere” for the black bands of mourning he wore after the death of Pope Leo X, the 16th century army commander was exhumed last November from his tomb in the Medici Chapels in Florence. Researchers also exhumed the bones of his wife, Maria Salviati.

The couple married in 1516, when she was 17 and he was 18. The marriage produced only one child: Cosimo I, who reigned as the first Grand Duke of Tuscany, creating the Uffizi and the magnificent Boboli Gardens as well as finishing the Pitti Palace....