Peter Orseolo was a Venetian, son of one of the best families. He became an admiral by age twenty, ridding the Adriatic of pirates. I figure that's an important thing for a commercial center that was built on an archipelago.
His father had served as Doge of the Most Serene Republic of Venice, but was not holding the office on August 11, 976 AD, when angry Venetian partisans locked the sitting doge, Pietro IV Candiano, in his palace and set it on fire. Their intention was to kill Pietro and his son, which they did. They did not intend to burn down half the city, but they did that also. Good thing Venice is on islands or the whole place might have burned down.
Peter was elected doge the following day. He dedicated all his energy and much of his money to rebuilding the city. First were the orphanages and hospitals and other forms of aid to the neediest. Later came the rebuilding of St. Mark's Cathedral.
On September 30, 978, Peter quietly slipped away in the night without even telling his family where he was going. Having exhausted himself with the restoration of the city, he became a Benedictine monk in the Pyrenees. Even his wife thought this was fair, though of course she was pretty well set.