Background
Prior to that, he co-ruled with his father.
Prior to that, he co-ruled with his father.
He was a nepotist intent on continuing the power of his own dynasty. However, Marinus, count of Comacchio, captured him and sent him back to Venice, where he soon died. Giovanni attacked and devastated Comacchio, but he could not hold it, because it was the pope"son
In 883, Giovanni negotiated a favourable treaty with the Emperor Charles the Fat.
Then the Venetians elected Pietro Candiano doge and Giovanni retired to private life. He tried to reobtain the dogeship on the death of Candiano, but failed due to his poor health.