Pietro IV Candiano (925–976) was the twenty-second (traditional) or twentieth (historical) doge of Venice from 959 to his death.
However, towards the end of his father's dogeship, Pietro IV revolted against him, but failed thanks to popular support for the doge.
Pietro IV had supported Berengar II, the Frankish king of Italy, while his father pursued a neutral policy.
Probably due to the turbulent recent past, Pietro imposed an oath of loyalty to his power, which was not a Venetian custom.
In a nepotist move, Pietro had the rival candidate to the position of Bishop of Torcello accused of simony, blinded and expelled so that he could install his brother Vitale to this bishopric.
For political reasons, Pietro repudiated his first wife, Giovanniccia, forcing her into the monastery of San Zaccaria.
In 966, Pietro remarried to Waldrada, the daughter of Hubert, the marquis of Tuscany, and a cousin of the wife of the emperor Otto I.
As the most powerful woman in Italy, Waldrada brought Pietro a large dowry both in money and properties in Friuli, the March of Treviso, Andria and the Ferrara area.
He thinks that the links Pietro had with Berengar II, especially those with Waldrada's father, when he was in exile (see above) initially made an alliance with Otto I unlikely.
Mor also thinks that the mentioned Vitale Candiano was not Pietro's brother, but the son he had with Giovanniccia, who had been forced into the priesthood.
Mor sees Pietro's mentioned military actions against Oderzo and Ferrara as being part of his opposition to Otto.
She had been a divorcee (which was frowned upon in those days) and she was originally Pietro's mistress whom he took into the Doge's Palace when he ousted his father.
This was a scandal and Pietro eventually yielded to the popular feelings and forced her to take a vow of chastity and go to the monastery.
The border north of Cittanova, from where the routes to northern Europe started, was no longer defined, which led to disputes and to a long fight that doge Pietro II Orseolo (991-1009) undertook in 995–96 against the belligerent bishop of Belluno.
[8][9] In 971 the Byzantine emperor John I Tzimisces imposed a ban on the sale military material (wood and weapons) to the Arabs.
The fact that the ban was adopted by the will of the popular assembly, rather than by a ducal decree crystallised the gulf that had developed between the doge and the people and the isolation of the former from the latter.
His living isolated from the people with a bodyguard of mercenaries hired from his mainland possessions and his manoeuvring to acquire family control of the top of the church made him all-powerful.
They were seen as being haughty and living in “proud and contentious isolation.” Waldrada was seen as being petulant and the fact that she was accompanied by Florentine guards was disliked.
Their bodies were thrown in the slaughterhouse, but were later recovered and buried in the monastery of Sant'Ilario, in Fusina, on the mainland coast of the Lagoon of Venice, perhaps because Pietro owned large estates in the area.
[13] As the fire spread, some 300 buildings were destroyed, including the churches of St Mark's, the old San Teodoro, and the newly completed Santa Maria Zobenigo.