In Siena , the political leaders objected to a bishop who was not only 24 , but also a foreigner .
At the age of twenty - four he was appointed by his maternal uncle , Pope Gregory XII , as Bishop of Siena .
In Bishop of Siena , the political leaders objected to a bishop who was not only 24 , but also a foreigner .
At the age of twenty - four he was appointed by his maternal uncle , Pope Gregory XII , as Bishop of Siena .