September 1, 978—Pietro Orseolo leaves Venice.

After two years’ successful administration, the rebuilding of the Basilica (at his own expense), and a series of threats against his life, the 23rd Doge Pietro Orseolo had had enough. In the middle of the night, without telling his wife or his son he left Venice:

The Abbaye St Michel-de-Cuxa is three kilometres South of Prades in Pyrénées-Rousillon.

“… there grew daily in him a desire to withdraw into monastic life. This desire was fostered, and came to a climax when a certain Fra Guarino arrived from Aquitaine. The Doge resolved to quit the world, but feared the opposition of his people. He resolved to escape secretly. On the night of 1st September … he left his palace, passed the lagoon to Fusina, found horses to Sant’ Ilario, rode rapidly through North Italy, and reached the monastery of S. Michele di Cusano in the (foothills of the) Pyrenees, where twenty-nine years of pious life and religious exercises procured him the honours of canonization.”
—Horatio F, Brown ‘Venice an Historical Sketch of the Republic’ (1895).

An accusation made against him in the Middle Ages to the effect that he entered the monastery out of remorse for having been an accessory to the murder of his predecessor is probably baseless.