Final answer:
The King of Naples died before his attempted conquest of Florence; the cause of death is not explicitly stated but may have been the plague, as it was a prevalent cause of death during that period and affected many significant figures according to historical records.
Step-by-step explanation:
The King of Naples died before he could successfully conquer Florence. It is not explicitly stated in the provided extracts how the King of Naples died; however, the context suggests that he may have succumbed to the plague, as this was a common cause of death highlighted and it impacted many significant figures during that time. The extracts mention other individuals who died of the plague in similar positions, and the plague's rampant spread across various regions is emphasized.
During these times, the plague was a recurrent disaster that caused the death of numerous individuals, from Giovanni Petrarca's son to Francesco Nelli, and as can be inferred, possibly the King of Naples as well. The disastrous effects of the plague in Milan and its subsequent spread to previously unaffected cities such as Avignon, where Petrarca's loved ones died, underscore the extent of the epidemic.
Historically, the plague has been responsible for countless deaths and has had profound impacts on the sociopolitical landscape, with rulers and commoners alike falling victim to its devastation.